7 


IMAGE  EVALUATION 
TEST  TARGET  (MT-S) 


1.0    \^^^  IIIM 


I.I 


u 

1^ 


iii  Mm 


M 
1.8 


1.25 


14    IIIIII.6 


Photographic 

Sciences 
Corporation 


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33  WEST  MAIN  STREET 

WEBSTER,  NY.  14580 

(716)  872-4S03 


0 


CIHM/ICMH 

Microfiche 

Series. 


CIHM/ICMH 
Collection  de 
microfiches. 


Canadian  Institute  for  Historical  Microreproductions  /  Institut  Canadian  de  microreproductions  historiques 


Technical  and  Bibliographic  Notes/Notes  techniques  et  bibliographiques 


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0 


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D 


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r~~|    Cover  title  missing/ 


Le  titre  de  couverture  manque 


I      I    Coloured  maps/ 


D 
D 


Cartes  giographiques  en  couleur 


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Encre  de  couleur  (i.e.  autre  que  bleue  ou  noire) 


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Bound  with  other  material/ 
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Lareliure  serr6e  peut  causer  de  I'ombre  ou  de  la 
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n 


n 


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D 


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obtenir  la  meilleure  image  possible. 


The  c 
to  thf 


The  ii 
possil 
of  thi 
filmin 


Origii 
begin 
the  la 
sion, 
other 
first 
sion, 
or  illii 


Theli 
shall 
TINUI 
whici 

Maps 
differ 
entire 
begin 
right  i 
raquir 
meth( 


This  item  is  filmed  at  the  reduction  ratio  checked  below/ 

Ce  document  est  filmi  au  taux  de  reduction  indiquA  ci-dessous. 

10X  14X  18X  22X 


26X 


30X 


■^ 


12X 


16X 


20X 


24X 


28X 


m 


The  copy  filmed  here  has  been  reproduced  thanks 
to  the  generosity  of: 

Metropolitan  Toronto  Library 
Science  &  Technology  Department 


L'exemplaire  filmd  fut  reproduit  grdce  d  la 
gin^rositi  de: 

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Science  &  Technology  Department 


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conformity  avec  les  conditions  du  contrat  de 
filmage. 


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Les  exemplaires  originaux  dont  la  couverture  en 
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la  dernidre  page  qui  comporte  une  telle 
empreinte. 


The  last  recorded  h^^^rre  on  each  microfiche 
shall  contain  the  symbol  -^^  (meaning  "CON- 
TINUED ").  or  the  symbol  V  (meaning  "END"), 
whichever  applies. 


Un  des  symboles  suivants  apparaitra  sur  la 
dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbole  -^^  signifie  "A  SUIVRE",  le 
symbols  V  signifie  "FIN". 


Maps,  plates,  charts,  etc.,  may  be  filmed  at 
different  reduction  ratios.  Those  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Les  cartes,  planches,  tableaux,  etc.,  peuvent  dtre 
film^s  d  des  taux  de  reduction  diffirents. 
Lorsque  le  document  est  trop  grand  pour  dtre 
reproduit  en  un  seul  cliche,  il  est  film^  d  partir 
de  I'angle  supdrieur  gauche,  de  gauche  &  droite, 
et  de  haut  en  bas,  en  prenant  le  nombre 
d'images  nicessaire.  Les  diagrammes  suivants 
illustrent  la  mdthode. 


m 


i    ^ 

^  ^  t 

3 

t 

a 

1 

•      .  •■    V  , 

4 

8 

6 

b^. 


DGTABTMEHT  Or  THE  IHTERIOR-U.  0.  OEOLOOIOAL  BUBYBT 
CHARLES  D.  WALOOTI,  DIHBCTOK 


RECENT  EARTH  MOVEMENT 


IN  TSK 


GEE  AT  LAKES  EEGION 


GROVE    KARL    GULBERT 


SZTBACT  FBOU  THK  SIOHTBEXTH  AMSITAL  REPORT  OF  THE  SURVET,  IgtS^ 
PART  U— PAPIRS  OdIBFI.T  OF  A  THEORETIC  NATURE 


WASHINGTON 

OOVBRNHBHT  PBINTINO  OFFIOK 

1898 


%"•- 


■=/ 


•u 


t  \\ 


RECENT  EARTH  MOVEMENT  IN  THE  GREAT 
LAKES  REGION. 

11 Y 

GS^ROVE    KARL    GILBKRT. 


685 


^, 


J 


CO  XT  H  NTS. 


Illtroiliu'tidli (!()l 

OliservntidiiM  liy  Mr,  Stiiiitz (iOl 

Kartli  niDvei'iuiits  iliiiiiij;  the  closing  opoclis  rl'  thr^  Ploistoeene  period (i03 

EeiiSdiiH  for  lej^iinliiif;  ;i  iirogressivo  moileiii  chiiiigo  as  probable (11)6 

Goiicnil  jiliiu  of  invrstiyiition (!09 

Available  ilatii 611 

(!agc  icii .lings fill 

HcndicH fil2 

Selortion  of  stations  an<l  yeura (!13 

Special  obsiTvations  in  IX'Mi (il4 

Disci. ssion  of  data  from  pairs  of  stations (il5 

SackcttH  Harbor  and  Charlotte 615 

Port  ('olborn(!  and  Cleveland 620 

Port  Austin  and  Milwaukee 624 

Kscanaba  and  Milwaukee 629 

Discrepancy  noted  by  Captain  Marshall 634 

Summary  of  results 635 

Is  the  land  tilting? 636 

Hate  of  movement 637 

Cieogra]>hie  ihanges  resulting  from  the  movement 63!) 

Plans  for  precise  measurement 641 

Selection  of  stations 641 

Conditions  controlling  ci|nipment 643 

Kqnipment 644 

Treatment  of  observations 645 

Suiiplemeut. — Investigation  by  Mr.  Jloselcy 645 

597 


i 


v.- 


*,.- 


i 


"  l.llSTRATliiNS. 


Plati:  C!V.   Kstiiiiry  :il  tli 


itli  "f  Ouk   Oicliaril  CroiiU.  iiiliMMs  County. 


New    Yolk 


Fill.    '••: 


!.  Miip  of  l.aurcntiiin  liiki'i 
'.II.  Ma|i  of  tlir  Iiiiii" 


lis  sliorc  lino . 


"I.").  M:i|)  ol'  till'  slioro  linr  of  lireiit  l.iiko  NipissniK 

f  tlie  sMrl'iir<'  of  tlic  Laiircntian  laU' 


Oil.  Annual  oscillation.^  o 

il7.  OHi'illations  of  the  .snrfaco  ol 


I.aki)  Michigan  dni'  to  ulian^is 


in  111' 


iilunio  of  tlio  lako 


9S.  lliajirani  illnstratiiiK  niellioil  of  ini'iisnri 


n;;  oartli  movements 


'.19.  Airan^icmen 


t  of  selected  .still ions 


Vnga 


(lilt 


I  ill  I 

t;o.-> 


llO'.t 


r.io 

lilO 


t>i:t 


10(1.  Kelalions  of  tlu^  sliores  of  tlie  (in'a 

tliron;j;li  tln'ir  ontlels 
1(11.  I'ropi 


t  Lakes  to  tlie  isoliases  ilrawii 


■d  svHtenis  of  stations  for  tlie  iireeise  meas 


nr'jment  ot  earth 


nioveiuent.s  . 


u'J'J 


(>10 


(112 


%■- 


\; 


y 


RECKNT  EARTH  MOVKMKNT  l\ 

HEIJIOX. 


THE  (;|{EAT   LAKES 


HV   (1.  K.  GIJ.UKBT. 


INTltODUC'ilOX. 

Tlie  geologic  liistory  oi"  the  oiiitli  shows  that  in  all  i)arts  of  its  sur- 
face tiiere  have  been  great  oseillation.s  of  level.  Modeiii  history  also 
records  upward  and  downward  movements  of  the  land  at  various 
points.  Tlie  modern  movements  are  of  small  amount,  hut  it  is  lielieved 
that  they  are  of  the  same  Idnd  as  the  ancient.  an<l  that  tlie  great 
changes  of  the  geologic  past  were  etl'ecteil  slowly.  Nearly  all  discov- 
eries of  modern  change  have  been  made  at  tlie  seasiiore,  but  tliere  is 
im  reason  to  suppose  that  the  land  is  now  more  stable  in  the  interior 
of  tlie  continents  than  along  their  (M)astal  borders.  Observations  arc 
restricted  to  the  coast  because  tlie  sea  level  atlords  the  best  available 
datum  plan(!  for  comjtarison.  The  jjrcsent  jtapor  discusses  the  stabil 
ity  of  the  region  of  tlie  fjaiirentian  laivca,  aud  uses  the  surfaces  of  the 
lakes  as  datum  levels  or  planes  of  rel'erence. 


OnSKUVATIOXS  IJV   MIt.  STL'NTZ. 

Ill  18G9  there  was  iiresented  to  the  American  Association  for  the 
Advancement  o"  Science  a  paper  by  (J.  It.  Stunt/.,  a  land  surveyor 
of  Wisconsin,  describing  certain  observations  on  Lake  Suiierior  made 
by  liim  in  18.j2  and  l.S5.'{.  II(^  states  that  in  those  years  a  certain  mill 
race  at  the  falls  of  St.  Marys  Kiver  was  entirely  dry.  As  St.  Marys 
Kiver  is  the  outlet  of  Lake  Superior,  its  volume  and  the  supply  of  water 
for  the  mill  race  depend  on  the  height  of  water  in  the  lake,  and  he 
therefore  inferred  that  at  that  end  of  the  lake  the  water  was  low.  lie 
also  states  that  a  small  stream  at  Piiidle's  mill,  entering  Lake  Sujierior 
not  far  from  the  outlet,  runs  with  swift  current  to  tlie  lake,  and  has  no 
widening,  marshes,  or  other  indication  tiiat  its  valley  overflows  by  tlie 
lake  setting  back  into  it.  He  then  describes  the  strongly  contrasted 
conditiou  of  streams  entering  the  lake  near  its  western  end:' 

As  you  go  westward,  tlie  (3iitoiiag(in  River  exhibits  a  sliglit  tilling  up.  The  valley 
iienr  the  mouth  shows  that  at  the  tiuio  it  was  oxeavuted  the  surface  of  the  lake  was 
lower  than  at  present,    'i'be  same  is  also  apparent  at  the  mouth  of  Uad  Hiver,  still 

•On  8onni  riTiMit  Ki'ol(>;;ioal  cliiiiigea  in  iiortheasteru  Wisconsin:  I*roc.  Am.  Ass.  Atlv.  Sri..  Vol. 
XVIII,  1870,  PI).  200-207. 

601 


602 


EARTH   MOVKMENT   IN   THE   GREAT   LAKES   KEOION. 


farthir  Wist.    At  tlio  inmith  of  Itoia  Uriili-  the  Baiiie  tliiiifr  18  oxbiliited,  only  to  a 

ureiiter  extent.     From  tliis  to  tlio  west  cnil  of  the  lake  not  only  doen  thr  liiko  set 

k  into  the  valleys  of  thi'  stieani.s.  liiit   the  waters  are  making  rapid  encniiich- 

s  on  the  hanks.     So  ra])iilly  is  the  fillinj;  hack,  that  the  depoHits  of  the  streams 

mn.i.   kci'p  jiaie  with  the  lillinf?  up.     The  eonseiiucnce  is.  that  there  is  a  large 

.ii:ii:.|i    11(1  )ioii<l  in  the  month  of  the  valh  y  of  Hois  lirnle  and  Amine<'an  River.     But 

i:o        .e  is  this  filling  up  more  apparent  than  in  the  liay  above  tne  mouth  of  the 

•t        )niH  h'ivcr.     In  several  jiarts  siilimcrgcd  slumps,  several  feet  helow  the  present 

level,  ar;)  found.     The  iiiimerons  inlets  serionncliiig  the  main  bay,  when  wo 

consider  the  nature  of  thi'  soil  and  llie  formation  (a  tough,  red  clay),  in  allot  whiili 

tbe  water  is  deep,  could  not  have  been  oxerivated  in  the  natural  eoiirso  of  events 

with  the  water  at  its  present  level.     The  testimony  of  the  Indians  also  goes  to 

strengthen   the  same  eomlusions.     At  thi^  time  of  running  the  ."state   line   above 

mentidued,  the  Indians,  ever  jealous  of  theii    rights,  called  me  to  a  council  to 


Fro.  it.T ^Inpof  Lnnrciititni  Inkofi. 

lD(|iilie  why  I  ran  the  line  through  Imlian  laud.  In  the  explanation,  I  gave,  using 
tile  language  of  the  law,  as  a  slarting  jioint.  the  lowest  rapid  in  ihe  St.  l.ouis  River. 
The  chief  immediately  replied  that  formerly  there  was  a.  rapid  ni'arly  opjiosite  the 
Indian  village.  Start,  said  he.  from  that  place,  ami  you  will  lie  near  the  treaty 
line,  .\lter  he  had  been  further  (piestioned.  1  learned  that  it  was  only  a  few  years 
since  the  river  was  i|nite  rajiid  at  the  Imlian  village.  .\t  the  time  the  said  line  was 
run  the  llrst  rapid  was  about  1  mile  by  the  stream  above  the  village.  I'nun  these 
facts  1  conclude  that  a  cliaime  is  taking  ]ila<'0  gradually  in  the  level  of  this  great 
valley. 

l-'roiii  those  diitii  Stunt/,  inters  "the  giiidiiiil  ii.se  of  wtiter  at  this 
[west]  end  nf  Iho,  hike  and  tiie  tiilling  iif  tlie  same  tit  the  east,"' iind 
it  is  evident  fntin  the  emitext  tiiat  he  releis  tliis  ehaiijie  of  the  water 
to  a  westwiird  eaiitinj;  of  the  htisiii,  the  western  iiait  beeoniiiifi  hiwer 
as  eonii)iired  with  tlie  eastern. 

So  far  its  I  iun  aware,  tliis  pajier  Inoiiches  for  the  first  time  the  idea 
of  ditVerential  elevation  in  tlie  Great  Lalves  region,  and  it  contains  the 


MOVEMENTS   IN    LATE    PLEISTOCKNE   TIME. 


603 


only  observations  that  bave  ever  been  cited  as  showing  reeent  changes 
of  tliat  charactor.  In  biter  years  the  snbje(;t  has  been  approached 
from  the  geohtgic  side,  anil  Dr.  .1.  W.  Spencer  has  expressed  his  ojjjiiiou 
that  a  warping  or  tilting  of  the  whole  region  is  now  in  progress. 


i:aj{tji  movkmkxts  Drmxc;  tiik  tLosixc  kih)Ciis  of 

IIIE  I'J.KISTOCKXK   PKHIOU. 

The  Great  Lakes  came  into  existence  in  the  latest  of  the  geologic 
periods,  the  Pleistocene.  Their  nnniber  and  i)osition  underwent  numer- 
ous and  important  changes  during  the  latter  part  of  the  i)eriod.  and  their 
area  and  drainage  systems  have  been  greatly  modified  even  within  tiie 
time  to  which  human  history  belongs.  In  late  Pleistocene  time,  while 
the  great  Lanreiitide  ice  tield,  which, just  before  had  covered  the  entire 
lake  basin,  was  slowly  growing  less  through  the  melting  away  of  its 
edges,  tliere  were  a  series  of  lakes  along  its  southern  margin.  These 
were  held  in  at  tiie  north  by  ice  and  on  other  sides  by  uplands,  and 
they  found  outlet  southward  over  the  lowest  passes  of  tiie  divide 
between  the  Liiiirentian  basin  and  the  liasins  of  tiie  Jlississi})])!.  Sus- 
quehanna. aii<l  Hudson.  Witli  changes  in  tlie  iiosition  of  the  ice  bar- 
rier, individual  lakes  were  from  time  to  time  divided  or  drained  and 
separates  lakes  united,  so  that  tin;  lacustrine  geograpiiy  had  a  complex 
history.  After  tlie  ice  iiad  wholly  disappeared  from  the  region,  the 
drainage  did  not  at  once  assume  its  present  system,  for  Lake  Huron, 
instead  of  overtlowing  to  Lake  Krie,  discharged  its  surplus  water  over 
the  pass  at  Xortli  JJay.  Canada,  and  thence  down  the  ^Lattawa  and 
Ottawa  rivers  to  tiie  St.  Lawrence. 

In  the  decipherment  of  this  history  much  use  is  made  of  the  shore 
lines  Of  the  vanislied  lakes.  Tliese  consist  of  sand  and  gravel  terraces 
that  were  once  deltas,  of  clitt's  aiul  strands  carved  from  hillsides  by 
the  waves,  and  of  spits  and  beach  ridges  thrown  nj)  by  the  same 
agency.  A  number  of  these  lines  have  been  traced  for  great  distances, 
and  wherever  thus  traced  it  is  found  that  they  are  no  longer  level, 
but  are  gently  inclined.  When  formed  they  were  of  course  horizon- 
tal, for  they  were  made  by  waves  generated  on  a  water  surface,  and 
the  fact  that  they  are  not  now  level  shows  that  the  land  on  which 
they  are  marked  has  undergone  changes  of  relative  height.  Tlie 
general  direction  of  inclination  of  the  shore  lines  is  toward  the  .south 
southwest,  showing  that  the  basin  of  the  lakes  has  been  canted  in  that 
direction.  The  amount  of  change  has  not  been  evi'rywheie  the  same, 
and  it  is  jirobable  that  the  directimi  of  the  canting  varies  somewhat 
from  jilace  to  jilace.  Where  several  shore  lines  aie  traced  on  the  same 
slope  the  lirst  made  are  usually  more  steeply  inclined  than  tlu^  last 
made,  and  hence  it  is  inferred  that  the  general  eliange  of  relative  alti- 
tude was  in  i)rogress  through  the  whole  e'poch  of  the  glacial  lakes. 
The  i>lane  of  the  Iroiiuois  shore  line  in  the  basin  of  Lake  Ontario 
descends  toward  the  south-southwest  at  au  average  rate  of  .'iA  feet  a 


604    EARTH  MOVEMENT  IN  THE  GREAT  LAKES  KE(iI()N. 

mile,  the  slope  being  steeper  at  the  north  than  at  the  south.'  The 
Oswego  slioie  line,  in  the  .same  basin,  slopes  iu  the  same  direction  at 
the  rate  of  more  than  3  feet  a  mile.  The  Warren  shore  line,  traced 
from  huiv?.,  New  York,  about  the  sides  of  the  Ontario,  Erie,  and  Huron 
basins  to  Pompeii,  Michigan,  is  nearly  level  in  the  Maumee  basin,  but 
rises  northeastward  with  a  rate  gradually  increasing  to  2  feet  a  mile. 
Its  northward  rise  iu  Michigan  is  1^  feet  a  mile.-^  The  present  south- 
ward iiK'lination  of  the  water  plane  of  Lake  Algonquin,  which  occu- 
pied the  Superior,  Michigan,  and  Uuron  basins,  ranges  from  a  few 
inches  to  .{  feet  a  mile.'  Great  Lake  Nipissing,  which  occupied  the 
same  basins  after  the  disa])pearance  of  the  ice  and  had  its  outlet  at 
North  Bay,  conformed  more  nearly  to  the  inesent  slopes,  the  general 
iuclinacion  of  its  water  plane  being  about  7  inches  to  the  mile.-' 


Fm.  04.— Map  of  tlio  TnK[Uois  ahuro  line.    Jfotlerii  wntpr  Innlics  nrc  Hhadeil.    A  lino  allows  tln-bound- 
(iry  oC  tho  uncii'iit  lake,    'i'lic  jiurullol  curves  are  i.-^ohiiHca. 

On  the  accompanying  maps  of  Lake  Iroquois  and  Cireat  Lake  Nipis- 
sing  (figs.  04  and  !).))  the  character  of  the  tilting  is  shown  by  means  of 
isobases,  or  lines  drawn  at  right  angles  to  the  direction  of  tilting.  All 
points  on  one  of  these  lines  have  been  uplifted  the  same  amount  since 
the  time  of  the  corresponding  lake.  If  we  think  of  the  i»laneof  the 
water  surface  of  one  of  the  old  lak?8  as  having  been  deformed  by 
uitlift  or  warping,  then  the  isobases  are  cont<nu'8,  or  lines  of  equal 
present  height,  on  the  deformed  i)laiie. 

Other  evidence  of  the  tilting  of  the  laiul  is  found  in  the  character  of 


>  J.  W.  Spencer,  Trnna.  Roy.  Sw.  Canada,  Sertion  IV,  Igsg,  pp.  12U134 1  a.  K,  Ullbert,  Sixth  Auu. 
Kepi.  CniniiiinHiont'i-H  of  tile  State  Keaervation  nt  Niasara.  Albany.  IHDO. 
»!•'.  I!.  Taylor,  Hull.  (ieol.  .Soe.  Ani.r.ia.  Vol.  VIII,  1897,  p.  6.1. 
"  K.  II.  Taylor,  A  Sliort  Ul»t<uy  of  the  liroat  I.iikeH.  Terre  Haute,  1897. 
«Ibid. 


U.   8.   GEOLOGICAL  SURVEV 


EIGHTEENTH  ANNUAL  HEPOHT      PART  II      PL.   CV 


^ 


ESTUARY  AT  THE  MOUTH  OF  OAK  ORCHARD  CREEK.  ORLEANS  COUNTY.  NEW  YUKk, 

Sc3i<>,   I  incFi        1,500  feet.      Figures  give  soundings  in  feet. 

The  watci  wjyb  aiu  bharply  incised  in  the  plain.     PaMial  rofillirg  is  shown  by  marshes.     Slack  w  .t  lake  lev(>t  roaches 

to  Cailton,  above  which  the  creeks  ate  shal'jw, 


MOVEMENTS    IN    LATE    PLEISTOCENE   TIME. 


(i05 


stream  cliaiinels  as  they  apitroach  lake  shores.  The  streams  reacliing 
Lake  Superi<ir  from  tlie  southwest  have  aheady  been  (lescribed  in 
the  (luotatiou  from  Stuiitz,  and  simihir  characters  are  found  in  the 
basins  of  Lake  Hrie  and  Lake  Ontario.  Consid('ral)lo  tracts  of  land 
alont;-  the  southern  sliores  and  about  the  western  ends  of  these  hikes 
are  smooth  phnns,  their  surfaces  having  been  leveleti  by  deposits  of 
tine  sediment  from  th(!  I'leistocene  hikes  Just  mentioned.  The  creeks 
and  rivers  traversinjjf  the  plains  have  readily  cut  the  soft  deposits, 
carviu};-  out  narrow  valleys.  In  the  upper  parts  of  tliese  valleys  the 
streams  are  shaUow  and  descend  with  lively  current,  but  on  approaching 


557~r 

:i 

C!Uca<fa 

^ 

Km.  ii'i. — Xlnjt  of  iho  Mlmrf  Ijix-  i»r  (Ji-cfit  lijikc  NipisMiiig.    >ro)lorn  water  bodies  are  sliadrd.     A  line 
HhowH  tlio  huiintlary  nl"  ttio  aii(-)<-iit  laUe.    U'ho  iiaralli'l  lines  are  IsobaHeH. 

the  lake  they  become  deep  and  sluggish,  the  change  usually  occurring 
several  miles  from  the  lake  shore.  Stated  in  another  way,  each  stream, 
instead  of  deboucliing  into  the  lake,  enters  the  head  of  a  long,  narrow 
bay  or  estuary.  The  origin  of  such  estuaries  is  well  understood.  They 
are  found  on  all  sinking  coasts,  and  their  meaning  in  this  region  is 
that  the  land  has  gone  down  or  the  lake  level  has  risen,  so  that  the 
waters  of  the  lake  occupy  portions  of  the  channels  carved  by  tlio 
streams  in  the  lowland  plain.  This  description  applies  to  the  greater 
number  of  streams  entering  Lake  Ontario  between  tlie  Genesee  and 
Don  rivers  and  to  those  entering  Lake  Erie  between  Cuyahoga  River 
and  Maumce  15ay.    ludividual  mention  may  be  made  of  Oak  Orchard, 


60fi  KAKTH    MOVEMENT    IX   THE    GREAT    LAKE8    KEGION. 

Eifiliteeninile,  and  Twelveinile  cioeks  in  New  York,  of  Twelveiiiile  aud 
Twentyniilc  creeks  aiid  the  Ciedir  and  Jlnmbcr  rivers  in  Ontario,  and 
of  Kocky  J{iver,  Black  Hiver.  Vermilion  l.'iver,  Old  Wonians  Creek, 
Pike  Creek,  Turtle  Creek,  and  <  )tta\va  Ki ver  in  ( )liio.  Kven  the  largest 
rivers  of  the  district,  inclndinj;-  the  (ienesee,  Niagara,  Cuyahoga,  and 
Jlauniec.  have  features  indicative  of  the  same  histny.' 

]{y  reference  to  the  ma])  (lis:.  !»■!.  ]).  <">-)  it  will  be  seen  that  the  outlets 
of  these  l;:i»es  aie  at  their  nortiieriimost  ixiints,  said  this  fact  is  related 
to  the  conditions  of  the  stream  channels.  The  water  level  of  a  lake  is 
maintained  by  the  balance  between  inflow  and  outtlow.  It  is  just  high 
enough  to  enable  the  outllow'ng  stream  to  carry  oft'  the  ex<'ess  fr{;m 
inllow,  and  the  height  of  water  on  all  shores  is  thus  detennined  by  the 
height  of  the  outlet.  80  if  thes  basins  are  canted  northward  the  out- 
lets are  thus  lowered  with  leference  to  other  parts,  and  the  waters 
recede  on  the  southern  shores.  If  they  are  canted  southward,  the  out- 
lets are  raised  and  the  vntcrs  are  made  to  advance  on  the  southeru 
shores.  Reasoning  from  effect  to  cause,  the  fact  that  the  lake  water 
invades  the  new-made  stream  channels  on  the  southern  shores  is  evi- 
dence of  the  southward  canting. 

It  should  not  be  ashumed  that  the  "drowning'"  of  stream  channels  ia 
restricted  to  the  traces  mentioned  above.  Those  tracts  are  specided 
because  they  fall  within  the  range  of  the  writer's  personal  observation 
aud  are  known  to  exhibit  the  phenomena  in  a  striking  way.  It  is 
believed  that  similar  features  may  be  found  wherever  the  local  con- 
ditions are  favorable  throughout  the  whole  coast  lines  of  Lake  Ontario 
and  Lake  ICrie,  about  the  head  of  Lake  Michigan  from  Manistee,  Mich- 
igan, to  Kewaunee,  Wisconsin,  and  about  the  whole  of  the  American 
shore  of  Lake  Superior. 


IJEASOXS  FOK  UEGAUDIXCJ  A  PKOfmESSIVE  MOUEllJiT 
CHAXOK  A«  PUOJIAULE. 

Independent  of  the  i)henomena  described  by  Stuntz,  there  arc  various 
considerations  tending  to  direct  attention  to  the  question  of  the  sta- 
bility or  instability  of  the  Laurentian  area  at  the  present  time.  The 
lirst  to  be  mentioned  is  purely  geologic.  The  epoch  during  which  the 
overliow  from  tht  upper  lakes  followed  the  valleys  of  the  Mattawa  aud 
Ottawa  is  detlnitely  .associated  with  a  certain  stage  of  the  Niagara 
River.  The  cataract  of  Niagara  is  at  the  present  time  increasing  the 
length  of  the  Niagara  gorge  at  a  somewhat  ra])id  rate.  The  fornnitiou 
from  which  the  water  lea])s  is  a  liiin  limestone  (iO  feet  tliick,  and 
beneath  this  are  shales  which  are  comparatively  soft  and  weak.  The 
cataract,  by  eroding  the  shale,  underniines  the  limestone,  which  falls 
away  in  blocks,  and  these  blocks  are  in  turn  utilized  by  the  water  as 
an  instrument  with  which  to  grind  the  shale.    WhirL'd  about  by  the 

<F.  B.  TB.rluriueutiouB  a  low  other  loiulitiiia  on  tlie  uaiiio  hikes:  Am.Uculoglat,  VoLXV.  WaO  fiD 
174-176.  o    ■>  I        .14" 


\' 


aiLiiKHT.]      PROBAHILITY    OF    PROGRESSIVE    MODERN.  CHANGE. 


(i()7 


water,  tlie  blocks  not  only  woar  away  the  face  of  the  slialc  clitf.  liiit 
drill  down  deeply,  .so  tliat  beneath  the  cataract  there  is  a  i>(>ol  nearly 
or  (jnite  200  feet  deej).  Working  in  this  way,  the  cataract  has  extended 
the  gorjie  several  hundred  feet  since  the  first  accurate  ineasurenu'nts 
were  made,  the  average  annual  rate  being  between  1  and  .">  feet. 

"With  tlie  jjpesent  airangcnieiit  of  tlie  drainage  system  the  Niagara 
carries  the  surplus  water  from  the  basins  of  lakes  Huron,  l^rie,  Miclii- 
gau,  and  Sui)erior;  but  when  the  upper  lakes  .sent  their  overtlow  to  the 
St.  Lawrence  by  way  of  the  Ottawa,  the  Niagara  carried  only  the  dis- 
charge from  the  I'lrie  basin.  Its  volume  was  then  only  one-eighth  of 
tlie  present  volume  and  its  jiower  was  corres])ondingly  less.  It  could 
not  mo\o  the  great  blocks  of  limestone  which  fell  from. the  dill',  and, 
instead  of  scooping  ont  a  dee])  jwoj,  as  now,  it  excavated  a  compara- 
tively shallow  channel,  whose  bottom  was  cumbered  with  limestone 
debris.  Owing  to  this  ditference  in  method  of  erosion  it  is  possible  to 
discriminate  the  parts  of  the  gorge  excavated  when  the  river  was  small 
and  when  it  was  large,  and  thns  to  determine  the  jdace  of  the  cataracit 
when  the  outlet  of  Lake  Huron  was  shifted  from  North  Hay  and  the 
Ottawa  IJiver  to  Port  Huron  and  the  St.  Clair  and  Detroit  rivers. 
That  place  is  at  the  head  of  the  Whirlpool  IJapids,  11,(100  feet  from  the 
l)resent  cataract.  Assnming  that  the  cataract  worked  at  its  present 
rate  through  this  distance,  we  may  compute  the  time  consunu'd.  At 
4.J  feet  a  year,  it  would  be  about  two  thousand  six  hundred  years. 
¥.  li.  Taylor,  making  allowance  for  various  qualifying  factors,  esti- 
mates tiie  time  to  have  been  not  less  than  live  thousand  years.' 

When  Lake  Huron  changed  its  outlet,  the  plane  of  its  water  surface 
exteiuled  from  the  pass  at  Xorth  I  Jay  to  the  i)ass  at  Port  Huron,  but 
the  North  Pay  i)ass  now  stands  140  feet  higher  than  the  I'ort  Huron. 
This  dilference  of  altitude,  anu>unting  to  G  inches  a  mile,  has,  there- 
fore, been  wrought  within  the  period  of  about  live  thousand  years.  lu 
view  of  the  gradual  nature  of  such  movements,  this  is  not  a  long])eriod 
to  assign  to  the  measured  chiinge,  and  it  is  natural  to  inquire  whether 
the  movement  is  not  still  in  progress. 

Dr.  J.  W.  Si)en<er,  who  has  devoted  nnich  time  to  the  .study  of  the 
Niagara  gorge  and  the  gh.iiial  lakes,  is  coutidout  that  change  of  level 
has  not  yet  cea.scd  and  that  it  will  eventually  turn  the  water  of  the 
ui)per  lakes  southward  to  the  Illinois  and  ^Mississippi  rivers,  leaving 
the  Niagara  channel  dry.  Addressing  the  American  Association  for 
the  Advancement  of  Science  in  1804,  he  said:-' 

Tho  end  of  tlie  falln  seems destiiiod,  it'  we  loiiil  tliu  fiitnro  liy  tliti  piist,  tii  tic  cllVcleil, 
not,  liy  till)  cnisioii  oxpondiiif;  itself  on  the  rocks,  Imt  liy  tencHtii.il  di'lbriniitiou 
tiiniiii);  till'  (lniiniij;(>  ol'iil!  Ilio  ujiper  Inkes  into  tlio  Mississippi,  by  way  of  CliicaKO, 
just  iis  tlio  iliiron  w.itors  wito  lately  tunioil  from  tins  Ottawa  into  the  Niagar.a 
drainai;i';  ami  at  tliu  rrcent  rate  it  would  seem  that  aliont  o. (100  oi- tl, OHO  years  at 
most  will  lie  needed.  'I'lie  ('lian;L;e  of  drainage  slionid  arrive  liefore  the  cataract  shall 
littve  receded  to  BnlValo. 


'  A  uliciit  lilntorv  (if  tlie  Omit  I.nkca. 

'I'lW.  Am.  Ass.  Ailv.  Sti.,  Vul.  XLIII,  18l)t.  ii.'JJIi. 


608    EARTH  MOVEMENT  IN  THE  GREAT  LAKES  REGION. 


Ui     I 


y 


Anotlibrcoiisidcratiou  ot  tlio  saiiif  tendency  is  found  in  the  condition 
of  tlie  estuaries  described  in  the  lasr  section.  xMost  ..1'  tlie  streams 
flowinj;  into  liiese  rise  in  districts  oi'  unconsolidated  drift  and  carrv 
forward  in  llond  time  a  considerable  load  of  detritus.  TJiis  is  dei)osited 
in  tlic  estuaries,  the  coarser  part  making  deltas  at  their  liead.s,  and  the 
finer  settling  as  mud  in  the  deeiier  water.  The  process  tends  to  convert 
the  estuaries,  first,  to  marsiies,  ami  then  to  dry  land,  but  in  most 
instances  little  progress  in  that  direction  lias  been  made.  There  are 
a  lew  creeks  rising  in  sandy  districts  which  have  succeeded  in  tilling 
their  estuaries,  changing  them  to  marshes;  but  as  a  rule  the  delta  at 
the  head  of  the  estuary  invades  it  but  a  short  distance,  and  the  marshes 
which  border  it  here  and  there  at  i)oints  .sheltered  from  the  Hood  cur- 
rents are  impassable  except  by  boats,  ami  have  the  appearance  of  sub- 
merged flood  pliiins.  These  characters,  from  their  clo.se  resemblance 
to  the  features  observable  along  the  subsiding  i)arts  of  the  Atlantic 
coast,  give  the  impression  that  a  slow  flooding  of  the  stream  valleys  is 
still  in  i)rogress. 

A  third  consideration  is  connected  with  the  record  of  recent  changes 
on  the  coasts  of  the  continent.  It  lias  long  been  known  that  the 
Atlantic  coast  south  of  Connecticut  is  subsiding,  and  I'rof.  G.  H.Cook 
was  able  to  determine  the  rate  in  New  Jersey  as  about  1'  feet  a 
century.'  Dr.  Robert  Bell  has  recently  collated  a  variety  <if  facts  tend- 
ing to  show  tliat  the  land  has  risen  in  the  region  about  Hudson  and 
.Tanu's  bays,-  and  he  estinnites  tiie  rate  u^  from  .">  to  7  feet  a  century. 
If  these  two  movements  are  parts  of  a  general  movement  att'ecting  the 
northeastern  part  of  the  continent,  then  the  Great  Lakes  region, 
approximately  intermediate  in  positicm  between  the  rising  and  sinking 
areas,  should  be  found  to  exhibit  a  southward  tilting. 

These  various  facts,  all  tending  in  one  direction,  are  sufVicient  war- 
rant for  the  working  hyiwthesis  that  the  tilting  of  the  lake  region 
demonstrated  by  the  slopes  of  the  old  .shore  lines  is  still  in  progress; 
and  the  writer,  who  lias  for  many  years  been  interested  in  the  problems 
of  the  Great  Lakes,  has  made  repeated  efl'orts  to  secure  an  investiga- 
tion by  which  the  hypothesis  might  be  tested. 

The  mode  of  investigation  first  suggested  was  the  establishment  of 
elaborate  observation  stations  at  three  points — Port  Huron,  Chicago, 
and  Mackinac.  Hy  a  suitable  series  of  ob.servations  at  these  points,  the 
relative  heights  of  benches  might  be  established  with  high  precision, 
the  water  surface  being  u.sed  as  a  leveling  instrument.  Then,  after  an 
interval  of  one  or  two  decades  the  observations  might  be  repeated  and 
any  changes  in  the  heights  of  benches  due  to  dift'erential  uplift  detected. 
The  matter  was  submitted  in  18!(0  to  the  Superintendent  of  the  United 
States  Lake  Survey  and  to  the  Superintendent  of  the  United  States 
Coast  and  Geodetic  Survey,  but,  though  it  was  received  favorably  by 
the  latter  i,flicer,  the  work  was  not  undertaken. 


'  Am.  Jour.  Sri.,  2(1  series.  Vol.  XXIV,  1857, 
»Am.  Jonr.  Sci.,  4tli  series,  Vol,  I,18!«!. 


PLAX    OK    INVKSTIOATION. 


COO 


Other  plans  were  then  ('(insirh^it'd,  aiid  it  was  lliially  dpcidcd  to  makii 
a  study  of  existiii}:'  ri'iords  of  lake  level,  and,  if  necessary,  sin)|)lenieiit 
tlieni  by  additional  observations.  The  results  of  this  investigation  arc 
set  fortii  in  tlie  folh)\viny  payes. 


<;KXKI5Ah  I* I. AX  or  IXVKSTKiATIOX. 

Variations  in  tlie  heiglit  of  the  ocean  level  at  any  place  depend  ehietly 
on  tides,  winds,  and  atmospheric,  pressure.  I>y  nu>aiis  of  lonjj  scries  of 
observations  tiie  ellect  of  tliese  disturbing  factors  can  be  eliminated 


JAN. 

FEB. 

MAR. 

APL. 

MAY 

JUNE 

JULY 

AUG. 

SEPT. 

OCT. 

NOV. 

DEC. 

SUPERIOR 

MICHIGAN- 
HURON 

ERIE 

ONTARIO 
1 

^ 



, 

~"~^ 

y 

/" 

\ 

^^.^ 

« 

y'' 

y 

/■"^ 



-^ 

y 

/ 

^■\ 





-- 

"~'^ 

\. 

^ 

/ 
/ 

\ 

\. 

"^■■v. 

-..^ 

/■ 

-•- 

^N 

s, 

'V 

~"— ■ 

. 

/ 

\ 

\. 

/ 

r 

\ 

— . — 

.^ 

^ 

Fln.no.  — .\imual  n.-rilljitioiis  nC  tlii'siirCai'i's  i-l"  Itii'  L.-iiirnitiiui  liikcs.     ('niii|iilril  IVmn  iiioiillilv  riifanH 
puliUslx'il  li.v  IIm^  Cliifl'  III'   Kniiiiiii's.  I'.S.  A.     Kuril  viTlli-il  »|iiiii'  ivpri'siMil.i  ii.\  inihis.     Tlio 

oliserviitioiiK  liii-  I.aki' SiipiTliii vit  the  iiiTiml  ISIi'J-lH'.l.l;  I'm- .Mirliiniiiilliiniii.  ISlili-lHU.'i ;  Ini'  Krii', 

l.s5.'i-|8'.t.'i  lor  (lutnrio,  l«ill-lMi."i. 

and  a  mean  level  obtained  which  is  ])ractically  uniform  from  year  to 
year  and  ilecade  to  decade.  The  height  of  the  water  surface  must 
depend  also  on  the  (|Uantity  of  water  in  the  ocean,  but  the  actual  varia- 
tions of  volume  are  so  small  as  compared  to  the  extent  ot  the  ocean 
surface  that  the  resultinj^'  variations  of  level  may  be  nej^lected  and 
the  mean  level  used  as  a  standard  for  the  discussion  of  ditlerential 
movements  of  the  earth's  crust.  With  tlu!  Great  Lakes  the  case  is 
materially  ditlcient.  There  are  variations  due  to  wiiul,  atmospheric 
pressure,  aiul  tides,  but  when  these  ha\  t*  been  eliminated  by  long  series 
18  (iKOL,  PT  2 39 


! 


610 


KAHTII    MOVKMKNT    IN   TIIK    (iUKAT    LAKES   KK«iI(»N. 


i 


of  oliscrviilions  tlu'  icsiiltiiiK  irit'iiii  li'vcl  is  far  I'loin  (•onrftiiiit.  varying 
from  season  to  si-asoii  anil  year  to  year  with  tlic  voliiiiie  of  water.  lu 
eacli  lake  tliore  is  an  annual  clianyc  of  more  tliaii  a  foot,  depending 
on  tlie  seasonal  ineciualify  bet  wei'n  gain  by  ])recii)itation  and  loss  by 
eviii)oratic)ii  (li«-.  !M'.),  and  tliere  is  a  still  greater  change  resulting  from 
tin'  ciiniulative  elfect  of  series  of  dry  and  series  of  moist  years.  The 
records  siiow  that  the  water  surface  in  each  lake  has  been  .several  feet 
higher  in  some  years  than  in  others.     (See  lig.  !>'.) 

For  this  reason  the  water  surface  of  a  lake  does  not  afford  a  datum 
]ilant'  by  reference  to  which  the  elevation  lU- subsidence  of  coasts  can 
ho  directly  determined.     Jortu'iately,  however,  there  is  an   indirect 


ISIO 

^ 

r> 



mo 

A 

-^ 

iPy 

A 

A 

b\ /Y  r  k./-'  ^ 

A 

A 

/\ 

i\ 

rA 

^/rsA 

^ 

A 

/N 

A 

r 

' 

J 

>/ 

J 

' 

Fill. UT.— (Ini'illaliiiiw  111'  tlin  siirfilr 


i»f  I.jilic  ^licliijinn  due  to  rlmiipcs  in  tlio  viilunit'  «!'  llic  lake. 
A\'isr(i!isiii.  t'nim  Angtist.  IH.'ll,  to  .Turn',  IH'.t".     Kiicli  )ior-i/outal 


method  by  which  ])ra(!tically  the  same  result  may  be  attained.  If  the 
mean  level  of  a  lake  surface  be  determiiu'd  for  two  parts  of  tlie  coast 
at  tlie  same  time,  these  tv.  o  planes  maybe  regarded  as  parts  of  the 
same  level  surface,  and,  through  referent^e  to  this  common  datum, 
fixed  objects  on  the  land  at  the  two  localities  can  be  compared  with  each 
other  so  as  to  determine  their  relative  altitudes.  If,  then,  after  au 
interval  of  time,  the  measurements  are  rejieated,  a  change  in  the  rela- 
tive height  of  the  fixed  objet^ts  may  be  discovered  land  measured.  The 
investigation  described  in  the  following  pages  made  use  of  this  method. 


l'"iti.  y?*.  — niaj;rain  illustrating  method  of  ineasnrin^  earth  nioviMurntH. 

The  fundamental  i)riuciple  of  the  method  is  illustrated  by  the  dia- 
gram, flg.  !)S,  in  which  A  0  B  is  the  cross  jjrofile  of  a  lake  basin.  At 
a  certain  time  the  mean  plane  of  the  water  surface  occupies  the  posi- 
tion .W.  r>y  means  of  the  engineer's  levtd  it  is  ascertaintd  that  a 
bench  mark  A  has  a  certain  height  above  the  water  plane  at  X,  and 
that  a  bench  mark  15  has  a  certain  height  above  X'.  The  difference 
between  tliest;  two  measurements  is  the  difference  in  altitude  between 
A  and  15.  After  an  interval  of  years  the  measurements  are  repeated. 
The  water  plane  then  stands  iit  some  ditVerent  level,  say  YV,  The 
height  of  A  above  Y  is  measured,  and  the  height  of  1!  above  Y';  the 


AVAILAIILK    DATA. 


(ill 


din'f'ience  betweoii  the  two  iiicasuienuMits  ftivi's  the  relative  liciKl't  "f  A 
sinil  li.  If  earth  lUDveiiiciits  have  owiiriTil  duriiij;'  the  interval  hcfweeu 
the  two  sets  (if  nieasm'eiiieiit.s,  the  seeoiid  (leteriniiiatioii  of  tlic  com- 
j)aiative  hei;;lit  of  A  ami  H  will  ditfer  from  the  lirst  determination, 
and  tiie  amount  of  ditl'erence  will  nKsasiire  the  ditferoiitial  earth  move- 
ment. 

\V\l  TjA lUu  !•:  I )  A'l' A . 

(iiii/r  niiiliiKju. —  In  order  toeliminate  the  temporary  elfecrtsof  disturb- 
\\\ii  factors.it  is  necessary  to  have  a  series  of  observations  ot  tlif  li('i;;ht 
of  the  water  surface  at  i-ach  of  the  localities  compared.     The  ;;afi;es  by 


T'       " 

n — 1 — r — 1 — 1 — 1 — 1 — 1 — 1 — r^ 

N            i 

.iuvA/VV^  V\a 

.^a:^^    -         -^n:^A.  .  A  A^ 

•  <J     , 

nH^^'^^^L 

\T^^ 

Coiiipilcd  midcr  IliiuliiTcIion  of  the  f"Iii''f  nf  KiijjiiH'erfl.  T*.  S.  A.,  Inirn  ^Mtif  rrailintzs  ut  Milwinikeo, 
Hpiu-n  |-t>j>re»i'titrt  a  caU'iiilai'  year:  t-arli  vf-rtirnl  spare,  iinu  I'liul. 

means  of  which  such  observations  are  made  are  of  various  kinds.  One 
of  the  simplest  is  a  graduated  ])laidj,  llxed  vertically  by  attacliinj;-  it  to 
a  dock  or  other  structure,  so  that  one  end  is  above  water  and  the  other 
below.  Sometimesthe  plank  isomitted  and  the  <rraduation  nnirked  u])on 
the  side  of  a  dock  or  i»ier.  The  heiijlit  of  the  water  surface  is  ascer- 
tained by  direct  comparison  with  the  lines  of  the  graduation.  Another 
form  of  jjafi'e  whiith  has  been  extensively  used  in  the  lakes  consists  of 
a  {^ra<luated  rod,  not  lixed,  but  held  in  the  hand;  with  this  the  distance 
from  the  water  surface  to  a  lixed  point  is  measured.  Usually  the  lixed 
point  chosen  is  above  the  water  surface,  but  at  v)ne  station.  Port  Col- 
borne,  it  is  the  submerjicd  sill  of  a  canal  lock.  Another  form  of  j;'a;.je 
includes  a  float  to  which  a  graduated  vertical  rod  is  fixed,  and  the 
graduations  of  the  rod  are  compared  with  a  fixed  point  on  the  land; 
01'  a  chain  attached  to  the  flitat  nniy  j)ass  over  a  i)ulley  and  carry  a 
counterpoise,  in  which  case  an  index,  fastened  to  some  part  of  the  (^hain 
or  counttu'poise,  moves  up  and  down  jiast  a  stationary  graduated  scale. 
There  are  also  automatic  gages  making  periodic  or  continuous  records. 
I'revious  to  tlie  year  l.SoO  records  of  lake  level  are  meager,  and  not 
of  such  nature  as  to  be  suited  to  the  purposes  of  this  investigation. 
A  general  account  of  them  is  given  by  Col.  Charles  Whittlesey,  in  Vol- 
ume XII  of  the  Smithsonian  Contributions  to  Knowledge,  and  a  fuller 
account  in  the  Iteport  of  the  United  States  Deep  Waterways  Com- 
mission for  18!)().  In  ISoit  the  investigation  of  lake  levels  was  under- 
taken by  the  United  States  Lake  Sui'vey.  Several  stations  were 
established  on  each  lake,  and  at  these  regular  observations  were  nuule, 
usually  three  times  a  day.     From  time  to  time  stations  were  discou- 


I. 


"•« 


..  <| 


■  .tl 


612 


I'.AIMII    MOVEMENT    IN    Till-:    (iKKAT    LAKK8    HE(!ION. 


in 
ii 


timicd  :iii(l  otliciH  were  cstablislit'd,  and  iiftor  the  close  (if  tlui  tleld  work 
of  Ihf  Laki'  Survti.v  tliu  observations  were,  in  many  cases,  continued 
by  ciViceis  of  tlie  I'hisiineer  Corps  in  cliarge  of  barbor  inipro"en»ents. 
With  refcreme  to  tlie  |)resent  iiivestiKation.  I  have  examined  I'nited 
States  Lake  Survey  and  other  [Jnited  States  en},'iueer  records  for  the 
foHowinj;  stations: 

On  Lake  Superior:  Superior  City,  Dulutli,  Ontonagon,  Manjuette, 
and  Sault  Ste.  Atarie. 

On  Lake  Midiifxan -Huron:  Cliicago,  Milwaukee,  (iraud  Haven,  Lock- 
p(ut.  Sand  Heach.  Tort  Austin.  I'ointc  Aux  Hanjues,  Tawas,  Ksuanaba, 
Thunder  Hay. 

On  Lai;e  ICrie:  .Monroe.  Hockwood,  CU'vehind,  Ashtabuhi,  I'",rie, 
Jintraio. 

( >n  Lake  Ontario;  i'ort  Dalhousie.  Niajjara,  Cinirhitte. Oswego,  Sack- 
etts  Harbor. 

Tiu'se  records  are  for  the  most  part  i)ublisued  in  tlie  form  of  montldy 
nu-ans,  but  the  iu<lividual  observations  are  preserved  in  the  lOugineer 
Ollice  at  AVasiiiujjton.  and  tlu!se  luive  been  made  accessibh*  to  mo 
through  the  courtesy  of  (leu.  William  1'.  Craighill.  Chief  of  l^ngincers. 
By  the  Canadian  J)epartinent  of  liailways  and  Camils,  I  have  been 
enabled  to  make  use  of  a  long  series  of  observations  at  I'ort  Colborue, 
on  Lake  ICrie,  the  head  of  the  Welland  Canal;  observations  at  Toronto, 
on  Lake  (Mitari(t.  have  been  furnished  nu(  by  the  city  engineer,  and 
observations  at  Collingwood,  on  Lake  Huron,  by  Jlr.  P'rank  JMoberly. 

liiiiclics. — As  gages  at  the  water  side  are  subject  to  various  acci- 
dents, it  is  rarely  possible  to  nuiintain  their  zeros  foi-  long  ])eriods  at  a 
constant  level,  and  unless  they  are  connected  by  leveling  with  bench 
uujrks  of  a  pernninent  character  their  records  have  little  value  f(U'  pur- 
l>oses  of  comparison.  I'revious  to  LS71  siu'h  connection  with  benches 
was  not  nnide  by  the  United  States  ]iake  Survey,  or,  if  nuide,  the  rec- 
ords are  lost.  There  were,  however,  certain  stations,  notably  Chicago, 
Jlilwaukee,  Cleveland,  i'ort  Colborne,  IJulfalo.  Charlotte,  and  Oswego, 
at  which  this  nnitter  had  received  attention.  The  structures  at  Chi- 
cago on  which  the  early  bench  marks  were  made  are  thought  to  have 
afterwards  .settled.'  At  Milwaukee  the  early  bench  marks  no  longer 
exist,  and  although  there  is  reason  to  believe  that  other  benches  were 
substituted  with  care,  my  researches  have  not  discovered  a  satisfac- 
tory reiiord.  Tlie  same  remark  applies  to  l>uftalo;  and  the  record  of 
theorigiiuil  bench  at  Charlotte  has  been  lost.  At  I'ort  Colborue  and 
Oswego  the  zeros  ol'  gages  are  pernninent  structures,  which  have  ])rob- 
ablysiitVered  no  change;  and  at  Cleveland,  although  the  oldest  benches 
no  huiger  exist,  it  is  believed  that  the  record  of  transfer  is  complete 
and  satisfactory. 

In  ISTO  Gen.  C.  I'..  Coinstock  was  jdaced  in  charge  of  the  United 
States  Lake  Survey,  and  the  scientific  methods  introduced  by  liiiii 

'ReiHiit  111!  l.liii;aj;i)  (.'Ity  Daluui  iiiiil  Cit\  I!biicIi  .Miuk.H.  In  W.  II.  Uwlj,'(s,  Cliicn),'ii.  189j. 


i 


SELF.CTIOX   OI'   STATIONS   AM)    YKARS. 


ci;? 


included  the  t'stablisliriR'iit  of  a  complt-to  system  of  hciiclH's  in  <((nnni',- 
tion  Willi  tli(!  K'lijics.  Krom  ISTli  until  the  eoniplt-tion  ol'  the  (ield  worU 
of  the  Liiko  Survey  there  was  itn  annual  inspeetion  (if  the  ;;aKes,  and 
the  relations  of  their  zeros  to  the  bench  marks  were  redeternjined  as 
otten  as  seemed  necessary.  I'rom  ISTl  to  1S78  tlio  mipervision  of 
{(ajii's  and  tlie  reduction  of  records  were  in  cbiirne  of  Mr.  ().  It, 
Wheeler,  and  from  IST'.t  to  l.SSL',  of  .Mr.  A.  I.'.  Klint.  Tiie  results  of 
the  present  investi^'iition  are  largely  indebteil  to  the  care  and  thor- 
oughness with  which  these  engineers  jjerformed  their  work. 

.SKLlOmoX   OF  STATION'S  AXn   'N'KAIJS. 

Tnder  the  general  method  outlined  above  the  first  stej)  was  the  selec- 
tion of  suitable  pairs  of  stations  on  the  shores  of  the  various  lakes.    As 


'■-J^r-lp^^^ 

f'^X^A 

"-^ 

'\^ 

J          J                          fj^j^Au 

\  i  / 

■"^ScuJceJt^'^^^ 

/ -V \^ 

yi  ^ 

CharlottB 

9 

1         A 

7l  ColSorne 

^^yit'leycLoTi  et 

Fin.  9n. — AiTiiiipement  of  ficlected  Htations. 


the  geologic  data  indicated  a  tilting  of  the  land  toward  the  south- 
southwest,  or,  more  precisely,  in  the  direction  S.  Ii7^  W,,  it  was 
desirable  to  have  e.ich  pair  of  stations  separated  by  a  long  distance  in 
that  direction.  As  the  hyi)othetic  change  was  exceedingly  slow,  it  was 
desirable  to  compare  observations  separated  by  the  longest  practicable 
time  intervals.  It  was  essential  that  the  gage  readings  before  and 
after  the  time  intervals  be  accurately  connected  with  the  same  benches. 
Consideration  was  also  given  to  the  fact  that  the  results  might  be 
vitiated  if  use  were  made  of  observations  taken  during  the  ])revalence 
of  storms,  when  the  water  is  sometinies  driven  by  the  wind  so  as  to 
staiul  abnormally  high  on  certain  shores;  i.nd  in  order  that  the  use  of 
such  observations  nught  be  avoided  it  was  important  to  select  years 
during  which  the  force  of  the  wind  was  daily  recorded.    With  these 


cu 


I'.AHTir    ^WOVEMKN'T   IX    THE    (JREAT    LAKES    REGION. 


consiileratioiis  in  view  the  available  data  were  examined,  and  tlie 
following  si'lectioii  was  made  of  stations  (see  li<;'.  !•'•>)  and  years: 

For  Lake  Ontario,  Charlotte  and  Sacketts  Harbor,  1874  and  lS>J(i. 

For  Lake  Va-w,  CIe\elan<I  and  I'ort  Colborne,  1.S5S  and  IS!).-). 

For  Lake  JIi(hif;an-IInron,  :\Iil\vauki'e  and  Tort  Austin.  1870  and 
18!l(l.  and  Milwaukee  and  Kscanaba.  1S7(!  and  lS!t(i. 

>'o  comparison  was  undertaken  lor  stations  ou  Lake  Superior. 

SPKCIATi  OJJSKIIVATIOXS  IX   1 «()(!. 

Certain  of  the  .s('lecte<l  stations  are  not  now  maintained  by  the 
United  States  engineers,  and  in  order  to  complete  the  data  it  was 
necessary  to  make  special  observations.  This  was  done  in  the  summer 
of  ISild,  dnrins  the  months  of  July,  August,  Sei)teniber,  and  October. 
The  lu'cessary  attention  was  also  i;iveu  to  bench  marks,  and  provision 
was  made  for  observations  of  a  special  character  at  the  regular  engi- 
neer stations. 

At  Sacketts  Harbor  use  was  made  of  a  gage  which  bad  been 
established  for  temimrary  ])uri)0scs  by  Maj.  W.  S.  Stanton,  l'.  S.  K. 
It  was  connected,  by  leveling,  with  an  old  bench  mark,  and  an  observer 
was  employed.  At  Charlotte  the  relation  of  the  gage  zero  to  a  bench 
mark  was  determined  by  leveling,  and  special  series  of  observations 
were  made  by  the  observer  employed  by  the  rnited  States  engineers. 
At  Port  Austin  a  new  gage  was  establishe<l  and  a  special  observer 
employed.  At  Milwaukee  and  Kscanaba  the  relative  lieiglits  of  gages 
and  benc'li  marks  were  determined  under  direction  of  Capt.  (leorge  A. 
'/Aim,  r.  S.  F.,  and  special  observations  wer<'  made  by  the  observers 
regularly  employed  by  the  United  States  engineers. 

The  "special"  observations  at  these  stations  consisted  of  series  of 
readings  intended  to  eliminate  the  ell'ect  of  the  osc^illations  called 
"seiches."  The  eipiilibrium  of  a  lake  surface  is  distuibed  not  only  by 
winds,  which  blow  the  water  toward  the  lee  shore,  but  by  inei|ualities  of 
atmos))lieric  ))ressure  occurring  during  thunderstorms  and  during  the 
l>assagc  of  cyclones;  and  the  impulses  thus  received  are  not  (]uickly 
dissipated,  but  cause  a  long-continued  swaying  of  the  water.  In  large 
lakes  these  oscillations  are  so  enduring  as  to  cover  the  interval  from 
one  disturbing  imjjulse  to  another,  and  keep  the  water  i)erpetually  in 
motion.  Xear  the  ends  of  the  lakes  and  in  bays  witii  gradually  con- 
verging sides  the  range  of  oscillation  may  be  as  great  as  I  foot,  and  it 
ordinarily  amounts  at  all  lake  stations  to  from  1  inch  to  I  inches.  For 
this  reason  a  single  observation  may  not  a])proNinnite  closely  to  the  mean 
level  of  the  water,  and  tlu^  actual  nu'an  level  can  be  determined  only 
by  a  series  of  observations  at  short  intervals.  In  arranging  the  work 
of  18!Mi  the  observers  were  instructed  to  record  the  water  level  every 
five  minutes  for  an  hour  each  morning  and  evening  of  all  days  when 
the  wind  was  light;  and  at  Sacketts  Harbor,  where  the  seiche  has  an 
exceptionally  long  period,  the  length  of  the  series  was  afterwards 
increased. 


;  I 


OILllKllT.l 


SACKETTS    HARBOR   AND    CHARLOTTE    STATIUNS. 


615 


I)ISCrS8I()X  OK  DATA  I'KO^I  PAlItS  OF  STATIOXS. 

SACKETTS  HAKBOR  AND  CHARLOTTE. 

Ill  I.S7-4  the  zeros  (if  ga.ues  at  tlicse  stations  wen'  points  maiki'd  on 
doc'ivs,  and  readinjis  were  made  by  means  of  j;iaduated  vertical  rods 
attached  to  lloats.  They  K'ive  tlie  distance  of  the  water  surface  below 
the  jiaiie  zeros.  At  t'le  time  of  each  observation  record  was  also 
made  of  th(^  direction  and  force  of  tlie  wind.  The  work  was  under  the 
direction  of  the  Cnitcd  States  Lake  Survey.  Mr.  A.  Wilder  was  the 
oi)server  at  Charlotte,  and  ^Ir.  Henry  Metcalf  at  Sacketts  Harbor. 

The  gage  at  Charlotte  was  put  in  place  in  Novendiei',  1S71,  and  the 
measurements  showed  its  zero  to  be  32.7  feet  below  a  bench  mark.  In 
January,  I.ST.'J,  its  zero  was  found  to  be  .'iL'.O.'i'J  tcei;  below  the  same 
bench  mark.  On  ^[ay  11,  1874,  it  was  a.uain  com[)arcd  with  tlu'  bench 
luark,  and  the  dill'crence  was  fouiul  to  have  increased  to  o.i.OO.".  feet. 
It  is  probable  that  this  change  of  .Ot  1  foot  was  occasioned  by  the  set- 
tling of  the  dock  to  wiiich  the  gage  was  attached.  A  manuscript 
report  dated  February  .'i,  1875.  says:  "The  baidc  is  here  partly  of  tim- 
bers and  partly  of  earth.  The  earth  has  been  washed  out  and  has 
fallen  away  from  the  timber  in  some  jilaces."'  Tia^  gage  at  Sacketts 
Harbor  was  also  found  unstable.  The  report  of  an  inspection  in  .May, 
1874,  states  that  the  zero  of  gage  "  has  been  lowered  ((.."i."),')  foot:"'  and 
a  rejiort  dated  February.  •>,  l.s7."),  says:  "This  gage  is  fastened  to  tiie 
timbers  of  an  old  and  unused  dock.  Tiie  whole  structure  is  ([uito 
dilapidated  and  unstable."  The  instability  of  gages  determined  the 
selection  of  time  for  the  comparison  of  stations,  I'.otli  gages  haxiiig 
been  comiiared  with  benches  in  May,  1S74,  that  at  (Jharlotte  on  the 
11th  and  that  at  Sacketts  Harbor  pro'oably  on  the  1 1th,  the  computa- 
tions were  based  on  a  period  including  these  dates.  Within  this  period 
selection  was  made  of  those  times  of  observation  wlien  tht;  wind  force 
at  both  stations  was  less  than  .'i  on  a  sciUe  of  lo.  Thus  treated,  tlio 
observations  of  ol  days  gave  51  eompaiisons. 


X 


GUI 


EAIiTir    MOVKMENT    IN   THE    (iREAT   LAKES    KElilOX. 


Comjiuldlioii  of  the  hriiiht  of  Ihv  giKjf  :iio  ill  Sarlella  Ilnrhnv,  Seiv  )'i)il:,  above  llir  i/age 
:civ al  Chuilolle.  -Ycif  York,  in  thv  epiinij  of  1x71. 


Iliiu 

■  ri'iHlin;;. 

D.i.v. 

Hour. 

Sllrlivltd 

Harbor 

(■Ii:irl..lli 

i 
DillcnnciN  | 

1 

1874.      i 

Fert. 

Fftt 

Fftt. 

A])!-.    17     1'  11.  111. 

T).  i:! 

:i.  i.-i 

2.2S     ' 

Ill     !i  ]p.  111. 

:>.  liii 

a.  (11 

2.  ;f2 

22     1)  li.iii. 

5. 2;f 

2. 118 

1         2. 25 

2:)      7  :i.iiL. 

.-..  It; 

2.80 

2. :!(! 

2  |i.  III. 

.-..  l.s 

2.  7X 

2.  10 

21      7  :i.  111. 

."i.  2(1 

2.8(1 

2.  Id 

2."'i     7  11.  111. 

5.  l.s 

2.  .SO 

2.  :i8 

2  p.  111. 

.■i.  1 1 

2.  .SI 

2.3(1 

27     7  ii.  III. 

."i.  IIH 

2.78 

2.3(1 

!•  p.  III. 

1.K8 

2.78 

2.10 

2X      2  p.  111. 

.-..  IM 

2.87 

1        2.20    ! 

!l  ]i.  III. 

.">.  no 

2.88 

!        2.18 

May      ;!     7  ii.  in. 

.■>.  ()(i 

2.  il") 

2.11 

1      7  .-1.  111. 

.-l.lli 

2.!!.". 

2.  48 

L'  p.  III. 

5.  (HI 

2.  !U 

2. 15 

i»  ji.  m. 

-).  10 

2.  !t4 

2.  22 

5     i)  ji.  111. 

.").  IH 

2.91 

1        2. 27 

6     it  p.  111. 

5. 12 

2. 85 

-        2.27 

7     7  a.  111. 

.-).  0(! 

2.S7 

2.  li) 

X      !l  p.  111. 

."■.  17 

2. 8.-. 

2.32 

11      '.1  |>.  111. 

Ti.  17 

2.82 

2.35 

11      'J  p.  III. 

.-..  12 

2. 83 

2.  29 

l."i     7  11.  111. 

").  17 

2.84 

2.33 

2  p.  III. 

."i.  2r> 

2.82 

2.43 

IK      2  p.  111. 

n.  la 

2.82 

2.  31 

!l  ]).  III. 

5.18 

2. 8.'i 

2.35 

20     7  11.  111. 

"i.  0.") 

2.83 

2.22 

2  p.  111. 

r..  10 

2.82 

2.20 

21      7  11.  III. 

5.02 

2.81 

2.21 

22      11  p.  III. 

.^02 

2.  H2 

2.  20 

21     7  a.  III. 

.').  12 

2.  !)5 

2.  17. 

I  2  I).  III. 

5.08 

2.  !)2 

2.10 

!'  p.  III. 

5. 08 

2.  ill 

2.17 

20     !»  p.  111. 

,"i.  (18 

2. 80 

2.  22 

27  1  7  11.  111. 

r..  (M) 

2. 80 

2.14 

!*  p.  111. 

5.10 

2  84 

2. 26 

2H     7  a.  11!. 

1.!I8 

2.83 

2.15 

U  p.  III. 

5.02 

2.83 

3.19 

QiLBEiti.]         SACKKTTS    HARI30K   AND   CHARLOTTK    STATIONS. 


fil7 


Comjiulation  of  the  hiiyhl  of  flieijagc  :ero  at  Siifketla  Ihirhor,  Xiiv  York,  almri-  tlie  ij(i(je 
:ero  <it  Cliarlotle,  .Vcir  York,  in  tlir  siiriiiii  of  i,S7/— Coiitiiiiicil. 


Day. 

1 

Hour. 

Gngci 

-eadiug. 

l>illen'iuo. 

Snckettn 
Uarbor. 

;  Chiulolte.  1 

1871 

Ftet 

J-..V. 

1 
Fret.        \ 

May 

30 

7  ii.iii. 

.->.oo 

2.81 

2,11.     j 

!t  ]).  m. 

5.  OS 

2.82 

2. 21    ; 

,)mii^ 

1 

!t  ]).  111. 

4.117 

2. 82 

2.1,-) 

>> 

7  11.  111. 

,"),  (10 

2. 8;{ 

2.17 

!)  ]).  111. 

.-..  02 

2.83 

2.17 

I 

'.)  )i.  m. 

5.10 

2.82 

2.28 

Ti 

!t  ]i.  111. 

.-..  00 

2.78 

2. 22 

<; 

7  :i.  111. 

,-).00 

2.78 

2.  22 

!l  ]>.  til. 

.-).  0!) 

2.  70 

2.  -M 

7 

7  ii.  111. 

,-..  1(1 

2.  711 

2.  ;n 

'2  p.  111. 

.■>.  00 

2.81 

2.11) 

8 

',1  |i.  Ill 

1.117 

2.81 

2. 10 

it 
Mciiii 

7  a.  Ill 

1.117 

2. 82 

1 


2. 15 

2. 217 

J-  .008 

1 

111  189(1  the  si'S't'  i'f  CliiU'lotte.  was  a  graduated  plank  s])ikpd  to  a 
pile  just  uovtli  of  tlie  western  abutuicnt  of  the  Koine,  Watertowu  and 
Ogdensburj;  Hailroad  biidge.  Tlie  readings  give  the  distance  of  the 
water  surface  above  tlie  zero  of  the  gage.  At  Sacketts  Harbor  the 
arraiigeiiieiit  was  similar,  the  gage  being  .spiked  to  an  unused  dock. 
The  observer  at  Charlotte  was  .Mr.  .1.  ^Y.  Preston,  harbor  master;  at 
Saekett.s  Harbor.  :Mr.  Wilbur  S.  McKee.  Observations  were  made 
morning,  noon,  and  night,  tlie  morning  and  evening  ob,servatioiis  being 
extended  into  series  whenever  the  water  was  so  little  agitati><l  liy  waves 
that  the  position  of  its  surface  could  be  determined  with  precision. 
As  the  times  selected  for  these  periods  of  observation  were  also  com- 
jiaratively  free  from  atmospheric  disturbances,  and  tlierefore  favor- 
able to  a  general  e(inilibriuiii  of  lake  surface,  tlie  coiiiputations  were 
restricted  to  such  times.  In  the  four  months  of  observations  there 
were  but  live  occasions  when  series  were  made  at  both  stations. 


618    EARTH  MOVEMENT  IN  THE  GKEAT  LAKES  REOION. 


Ci>mi<iitulion  of  flic  hviiihl  of  Ihe  </(i<ie  :ero  al  SacitlH  llai-lmr,  .Xcir  Yorl,  ohon-  the  ijuije 
:iio  (il  ChurloKi.  Siif  1  oii',  in  Ihe  Huiiimer  of  !SOi:. 


Hnnrnf  roinmi'iiiin;; 

1     Niiiiiliornf 
tive-iMiiiiiir 
niidiiijZi^. 

>liiin  ..f 

ri'iKlin^s. 

DilltTi'l.i'*'. 

Bate. 

Sncki'tts 
Harbor. 

Ch.ir- 
1     l< 

.^.ick. 
Ills      Clmr- 

Ii..r. 

Siickitlli 
ll;ilh..I-. 

Clinrlottc 

niiarliittf 
iii1nii.'4  Sack- 
ill«  Harlior, 

1896. 

1 
1 

rret. 

Frft. 

Alls;,   s 

7.  1.5  :i.  111. 

7  a.  111. 

iH       i:i 

f.!l8l 

(1.  iW-' 

—0.  OL'2 

S 

(t. .'!()  ]).  in. 

li  p.  111. 

i:!       ii; 

(i.»12 

().!«! 

(1.  OL'L' 

Sept.  !l 

.~i.  ;tll  ».  in. 

7  .'i.  111. 

13       i:i 

0.  :i.".i 

0.  i-M 

(1.077 

n 

5.(1(1  p.m. 

(1  ]).  111. 

i;i       i:i 

(t. 'J7(l 

0,  ;!(iH 

0.  Oils 

Oct.  27 

X.  l.">  a.  111. 
11           .... 

7  11.  ill. 

\r,       u 

—0.1  IS 

—(1.0  IS 
1 

0. 1(10 

\Iej 

-f  0.  05.'. 

1 

±o.ou 

The  beiicli  at  Olmrlottc  is  a  iiiarlv  (Hi  tlic  iiiiper  surface  of  tlu'  water 
table  of  till'  old  lijilitliimse.  The  walls  of  the  hiiildiiif;'  show  no  ciacks, 
and  there  is  every  reason  to  believe  the  beiieii  stable.  On  May  11, 
187 1,  the  zero  of  gajj^e  was  found  by  Mr,  !•>.  S.  Wlieeler,  assistant  engi- 
neer I'liited  States  Lake  Survey,  to  be  .'>.'?.003  feet  below  this  beiieh 
mark.  On  .liiiie.'iO,  ISOO,  f  leveled  from  the  zero  of  the  present  nage 
to  the  beiu'h  mark,  obtaining  38. !>.')(»  as  the  mean  of  two  measurements. 
On  July  11.  bsi)7,  .Air.  Warner  W.  (lilbert  obtained  38.)).14  feet  as  a 
mean  of  two  measurements. 

The  only  bench  mark  existing  at  Saeketts  Harbor  in  1S71  and  l.S!H» 
is  a  point  on  the  upjier  ourcr  edge  of  the  water  table  at  the  northeast 
eorner  of  the  stone  building  known  as  the  Masonic  Temple.  lu  May, 
1871.  this  was  determined  by  Mr.  Wheeler  to  be  IL'.^L'.")  feet  above  the 
zero  of  gage.  On  June  l.'S,  iS'.Ui,  by  duplicate  measurements,  I  found 
it  to  be  i;().42."»  feet  above  the  zero  of  the  i)resent  gage.  The  building 
bearing  this  mark  rests  on  a  foundation  of  bed  rot.'k,  but  -.levertheless 
has  yielded  to  such  extent  that  its  walls  are  cracked.  1  was  informed 
that  the  eraekiiig  and  repairing  of  the  walls  took  place  some  years 
previous  to  1871,  and  regard  it  as  probable  that  there  has  been  no 
change  since  that  date  in  the  height  of  the  bei.ch  mark. 


ciiiHKKT.]        SACKKTT8    HARliOR    AND    CHARI.OTTK   STATIONS.  019 

These  sovcral  data  arc  combined  in  tlio  Ibllowinf,'  table: 

CoiHjiHlalion  of  till-  heiijht  uf  Ihe  henili  marh-  <il  Clidi-lnlfi;  .Vcir  York,  tihoi-c  llic  heiirli  murk 
III  SiirhellH  lliirlinr.  \t  w   \''iil,\  in  /a,'/  ami  ISfn:, 


IS'.tti. 


cliiirliitin    lii'iirli    iiiarii    iiliovo   ('liiirlotte  !         yeci.  y,rt. 

Knyr  /I'M) -|-:i;!.  (Ki:!        -)-;;s.  icio 

Cliiiilcilte  );iino  zero  ;iliove  Sarkctts  Ilur- 

lidi' ijii^e /em —  2.'2\~         —    iMdri 

SiicKctts  llarlior  an'^i.'.  zcroabovn  SarUetts 

llailHir  lieiiili  maik — 1:.'.  L'L'.'i         — I'd.  I:;.") 

Slim    (if    aliiivi!  =- Cliarlotte    lii'iicli  ! 

inarkiiliDvoSaiUetts  llailKirlionrli 

in:irk +l«.ri:il         +ls..l7(l 

Ilili'creiU'O I  — (I.  diU 


The  results  of  the  coiniJUtations  indicate  tliat  tlie  heiglit  of  the  Char- 
lotte bencli  niai'ii  above  tlie  Sael^etts  llaibor  bencli  inaik  has  diniin- 
islied  in  twenty-two  years  to  tlie  extent  of  0.0(!1  foot.  This  ([nantity  is 
the  aljicbraie  sum  of  six  otluT  iiuantities,  two  measurements  tln'ough 
water  leveliiifi'  and  four  measurements  by  tlie  eii}^iiieer"s  level.  Tiie 
probable  errors  of  the  water  levelings  are  J.O.OOS  and  J  0.011:  foot;  Ihe 
probable  errors  of  my  own  instrumental  leve^Migs  were  each  J  0.01  foot. 
AssifiniMfi'  the  same  precision  to  the  earlier  leveliuKs,  we  obtain  for  the 
resulting  ([uantity  (0.0(U  loot)  a  probable  error  of  about    I  .((.!  foot. 

This  probiible  error  attemi)ts  to  express  only  such  deviations  from 
accuracy  as  are  exhibited  by  the  discordance  of  observations;  it  does 
iiot  include  errors  of  the  class  called  constant.  Tiie  result  nmy  bo 
vitiated  by  the  instability  of  either  bench  or  by  river  freshets  in  ISTl, 
and  there  are  ([ualilications  related  to  tides  and  cyclonic  jiradient. 

The  data  at  Sacketts  Harbor  are  not  subject  to  errors  from  stream 
floods.  The  ffas'cs  at  Charlotte  wercMin  the  baidc  of  the  (ieueseo  I'iver 
near  its  mouth.  The  channel  is  deep,  and  at  ordinary  liver  stages  the 
current  is  so  gentle  that  river  level  and  lake  level  are  the  same,  but  in 
time  of  river  Hood  the  river  level  is  somewhat  higher.  In  ISOii  uo  tlood 
periods  were  imduded,  but  the  rec(uds  for  IST  I  are  not  full  enough  to 
insure  frecilom  from  tlood  intlnences.  If  the  Charlotte  data  include 
errors  diu-  to  that  (lanse,  their  correction  would  increase  the  comi)iited 
change  of  relative  height. 

The  tides  of  the  (rreat  Lakes  are  so  simill  as  to  be  masked  by  the 
seiches,  but  they  are  nevertheless  of  sutlicient  magnitude  to  atVect  an 
investigation  of  this  sort.  Lieut.  Col.. 1. 1).  Graham  del.  iinined  a  lunar 
tide  of  Lake  Michigan  at  Chicago  amounting  to  1 'i  iiu'iies  ami  a  spring 
tide  amounting  to  .'iA  iiudies. '     (ten.  C.  15.  Comstock  determined  a  luiuir 


I  Ann    Iti'pl.  (  hiiii,!'  Dnjjiin'irn,  V.S.  A.,  lui-  iMki,  ii.  :;uO. 


(il'O  EAKTH   M0VI;MEXT    IN'    THE    GREAT    EAKE.S    RElilON. 

tiilc  (if  Liikc  Micliijriin  at  Mihviiuke.c  of  1  incli  iiiid  a  solar  tide  of  one- 
liiilfiiicli:  and  a  tidii  of  1  A  jikIk's  was  loiiiid  at  the  west  end  of  Lake 
Snj)eri()r.  ■  Tlic  tides  of  Lake  Ontario  have  not  been  investigated,  and 
tlieiefore  a  conei'tion  for  tlieni  can  not  lie  ajiidied.  It  wonld  be  (juito 
]iossible  to  elirninale  their  elVect  by  making  the  periods  of  observation 
inelndecoini)lete  tidal  cytdcs;  'lut  tlie  local  conditions  gave  greater 
iniportanec  to  other  criteria  for  tlie  selection  of  times.  An  inspection 
of  dates  with  reference  to  tidal  cycles  shows  that  tlie  observations  are 
so  distribated  tliat  the  inllnenee  of  tide  can  not  be  great. 

A  complete  coniparalivo  discnssion  of  lake  levels  slionld  also  take 
aeconnt  of  differences  of  atniosidieric  jiressnre.  It  is  evident  that  in 
a  condition  of  c(|uilibrinin  the  level  water  snrface  ninst  bodelbnned  by 
local  ine(inalities  of  atmospheric  pressnre,  and  the  effect  of  jiressnre 
differences  of  conrse  coexists  with  ine(pialities  dne  to  other  cause.s.  In 
]ilanninj,-  these  conijiutations  the  intention  was  to  apply  corrections  for 
barometric  gradient,  bnt  this  intention  was  afterwards  relintjuished 
becanse  of  the  difliculty  of  properly  discussing  the  available  baro- 
metric data.  Such  examimition  as  was  given  to  the  subject  led  to  the 
ojiinion  that  during  the  storndess  periods  selected  lor  the  comi)arison 
of  gage  readings  the  error  arising  from  the  neglect  of  the  pressure 
correction  is  small. 

PORT  COLBORNE  AND  CLEVELAND. 

The  character  of  the  gage  used  at  Cleveland  in  1S.">.S  is  not  describoil 
in  the  records  I  have  seen.  Neither  is  the  name  of  the  observer  given, 
bnt  various  circumstances  indicate  that  the  readings  were  made  either 
by  Ool.  Charles  Whittlesey  or  under  his  immediate  direction.  The 
readings  give  the  distance  of  the  water  surface  below  the  high- water 
level  of  1838,  ami  that  level  was  adopted  by  the  United  States  Lake 
Survey  as  the  ]ilano  of  reference  for  all  observations  on  Lake  Erie.  At 
Port  Colborne  the  upper  sill  of  Lock  No.  27  of  the  Welland  Canal  was 
the  zero  of  nn-asurement.  and  the  measurement  was  made  by  the  lock 
master,  .Mr.  John  Mc(iillivray,  by  thrusting  a  graduated  jjole  into  the 
water  until  the  end  rested  on  the  lock  sill.  As  the  reference  point  at 
Cleveland  was  above  the  water  surface  and  that  at  Poi't  Colborne 
below,  their  difference  in  height  is  obtained  by  adding  the  two  readings. 
Most  of  the  observations  at  Cleveland  were  nmde  at  8  a.  m.  and  the 
observations  at  Port  Colborne  at  noon.  At  Port  Colborne  the  direc- 
tion of  the  wind  was  recorded;  at  Cleveland,  the  direction  and  iovv.e., 
I  do  not  know  the  scale  of  force  emjiloyed,  but  the  record  numbers 
range  from  (»  to  5.  All  observations  at  both  stations  were  rejected 
wlieu  the  wind  force  at  Cleveland  was  recorded  as  greater  than  1. 

Th(^  gage  zero  used  at  Cleveland  in  ISOo  was  the  upper  edge  of  a 
cleat  nailed  to  a  jdaidc  forming  one  wall  of  a  well  in  a  wharf.     From 


I  Ann.  Itciit.Chli'IcilKnginciTii,  U.S.A.,  lur  187-,  i>\i.  10;i;),  1U3.\  1040;  1873,  up.  117:i,  Illi'J,  lliU, 


(IIUIKIIT.) 


PORT   COLHORNE    ANIl   CLEVKf.AND    STATIONS. 


r,2\ 


this  till'  ohsorvia-  measured  to  tlie  water  surface  in  tlie  well  with  a 
graduated  rod.  Tiic  ga^e  zero  was  set  at  the  level  of  hinh  water  in 
1.S3.S,  wliieli  is  mentioned  in  the  records  as  -tlie  i)huie  of  reference."' 
Three  observations  were  made  daily,  at  7  a.  ni.,  1  p.  ni.,and  7  p.  in.,  the 
work  heinj;' under  the  direction  of  the  liiited  States  I'lnjiineers.  At 
I'ort  C'oll)orne  observation  was  made  by  means  of  a  lloat  connected 
through  a  chain  with  a  counterpoise,  and  was  therefore  indirect;  but 
the  readings  were  ehei^ked  by  occasional  observations  with  ajiole,  after 
the  method  of  l.sr»S.  An  index  on  the  connterpoist^  was  so  adjusted  as 
to  indicate  on  a  scale  the  depth  ol'  water  on  the  lock  sill.  I  inspected 
the  gage  in  l.S!»(i,  linding  it  in  close  adjustment,  except  that  an  error  in 
cither  direction  of  a  fraction  of  an  inch  might  arise  from  friction.  The 
observer  in  1S!»."»  was  ,Mr.  .lohn  llenshaw.  Jn  the  following  table  the 
readings  at  \\>vt  '^'olborne,  which  were  ict^orded  in  feet  anil  incl",'s.  have 
been  convertetl  to  feet  and  hundredths.  The  record  of  wiiul  at  the  two 
stations  was  the  same  as  in  l.S,"»S,  and  there  were  also  available  the  wind 
ami  ])ressure  observations  of  the  Tnited  States  Weather  linieau. 
From  ail  inspection  of  these  data  three  jjerious  were  selected  tor  coni- 
liarison:  June  L'S  to  -Inly  .'!,  July  IS  to  liS,  and  August  3  to  IS.  These 
lieriods  are  so  related  to  the  tidal  cycle  as  nearly  to  eliminate  tidal 
error. 


■^1 


CiniijintitliDn  ftf'  llif!  Iititjiif  nf  thr  '   plinir  of  rrl'irt'iu'r  ^'  at   ^'Irrrltanl.  (thiti.  nh'H'r  fhi   nill 
(if  I. ml,'  \o.  ,.'.'  '(/'  llic  U'eUantl  I'tiunl  iil  I'art  (iilhiirnv,  Onlario,  in  IS'oS  and  76'.'',7. 


Diilc'. 


18.'W. 
Alljf.  20 


Si'pt.  1 
:) 
fi 
(( 

u 

ii> 


:iu  ; 
Oct.      4  i 

10  I 


i?ii:  at       iiiii  ill 
Clfv...    I'.iiiCcil 
IiiidI.       Iinnit'. 


I;i;niiii;is  ill  Cii'vi'Iiirnl. 


Dill. 


It. 


8.11 
S.  ,1 
.'i.  0 
8.(1 


9..'. 
11.  1 


I..'. 
II,  !l 

l.li 
3.U  i 


n.  In. 

u  : 

u  i; 

U  (1 

11  II 

u  :; 

II  I 

II  (I 

l:l  11 

II  1 

U  U 

n  .■( 

i:i  11 

i:i  '.I 

U  :i 

U  II 

i:i  11 

i:i  .'j 

U  II 

11  -J 

II  .•. 

14  II 
13  lU 


4.0 
■-'.  0 


II. 
l."i 
!,■. 

l.'i  U.  .'■ 
II     ,-..11 

II  11.11 

11  11.2 
1 1  ^■.  II 
14     .^.L' 

14  111.4 
II  .■(.  7 
11  0,7 
1 1     ■<.  0 

l;i  11. :i 
II  '.1.7 
14    II.  :i 

14  11. H 

14  II.  .•> 
l.T     11.11 

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1,".  7..') 
1.)    1.0 

15  1.0  I 


7  ii.  111. 

l|..iii. 

7]i.  111. 

1 
Menu, 

'ml  C.il- 
liiniH-. 

Mini. 

r,,i. 

IWI. 

IWI. 

IWI. 

/■.,/. 

F.'l. 

L'S 

:i.  :io 

:i.  .-.o 

3.411 

111.  nil 

14.3-.' 

•Jll 

:i.  :<:< 

:i.  .-11 

:i.  ;i3 

:i.  .■.3 

10,7,-i 

14. 'JS 

:iii 

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;i.  .'11 

3.  y.i 

!>.  j.i 

1 1 ,  lis 

14. Ut 

1 

;i.  (Ill 

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3.  Ill 

111.  7.'i 

1  1.  l.-i 

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:i.  47 

:i.  4.". 

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3.411 

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14.32 

:i 

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;i.  Iiu 

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11.1111 

11.73 

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3.  70 

3.  OS 

111,  7,-. 

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3.  .'.:i 

3.  07 

ill:,-. 

11.112 

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:!.87 

3.  (VI 

3.01 

11. ml 

U.iil 

'J:; 

;i.  iiu 

;i.  .'.II 

3.011 

3.  07 

111.75 

14.  12 

•j:i 

:i.  I'll 

;i,  70 

3.70 

3,07 

111.  S3 

H..MI 

■-'1 

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;i.  on 

3.711 

3.  i;ii 

111.  S3 

11,  111 

nr. 

:!.  ~- 

:i.  7:i 

:i.  S'J 

3.70 

10.07 

II,  13 

X 

:i.  "11 

3. 7:i 

3.  03 

3.00 

11.1111 

11.011 

■J7 

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'.'.  "11 

3.  3'.' 

3.  .V.I 

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111.  7.-1 

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:{ 

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3.,«11 

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11,1111 

ll.sil 

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3.711 

111.  .".-i 

14.28 

n 

;i.!iii 

3.  73 

3.  70 

3.7S 

11.33 

13.11 

7 

3.03 

3.  IP.-i 

3.  00 

3.  S3 

11.7.-> 

15.  .'iS 

G22       KAHTii  mo\'Kmj;nt  in  the  gkeat  l.\ki:s  kegion. 

Cmni>iit,iti<m  of  the  hiijhl  ,if  the  '-jihini'  nf  refenne.e"  at  Cleielaiid,  Chh,  ahore  the  Kill 
of  Lock  .\o.  :Tofthe  n'tlliiiid  (dual  at  I'orl  Cilhoriie.  Ontario,  in  1S:S  and  is:)r,— Von- 
tiniK'cl. 


lioail- 

D.I..             '"-"' 
I;lll(l. 

Rind- 

iMH  111 

I'.nlCi.l 

burnt'. 

II.  in. 
v.;    (i 
14    ;i 

Sinn. 

I'L  .'ii. 
14  III  0 
1.-.    .1.2 

Dal,'. 

1811.1. 

■\»li-    » 
0 

Keii 
7ii.  in. 

liligH  at  Cli'vclniiil, 

Kcad- 
iiignt 
I'lirt  Col- 
borne. 

Sum. 

1p.m. 

7  p.  111. 

Fee,. 
3.80 
3.69 

Menu. 

Feel. 
3.72 
3.07 

IS.'JS.       '   ri.    III. 

(1,1.      11         1      1." 

11         11'. '.' 

Feel.       Feel, 
3.75       3.00 
11.  72         3. 70 

Feet. 
10.07 
10. 83 

7','i'(. 
14.31) 
14.50 

1.^.        11   11.11 

II    :! 

l.-i    2  0 

10 

3.110 

3. 7.1 

3.70 

3.78 

10. 70 

14.53 

III        0   111..'. 

14    .". 

If,    3..-. 

11 

:i.  80 

3.50 

3.04 

3.05 

10.07 

14.32 

IS        1      .1.0 

14     2 

1.-.    7.0 

12 

3.  .14 

3.78 

3.(18 

3. 07 

11.110 

14.07 

19       1     4.0 

i:i    .-. 

14    0.11 

i:i 

3.00 

3. 07 

3  00 

3.02 

10.83 

14.45 

L'li     1    ■:.  11 

i:i    3 

11    .10 

14 

3.08 

a.oj 

3.70 

3. 08 

11.00 

14.  08 

L'l        1     4.7 

l:i    2 

14    0.7 

1.1 

:i.fll 

3.72 

3.05 

3.00 

11.00 

14.  00 

■-'■.'       1     4.  .■^ 

13    7 

14  11.8 

10 

II    fl" 

3.1I9 

3.07 

3.59 

10.  83 

14.42 

■::,     1    !..■< 

rj   .'i 

i;i    11. « 

17 

3.  70 

3.08 

3.70 

3.09 

10.75 

14.44 

■jr,      1    4. 4 

12    7 

i;i  11.4 

18 

3.  SO 

3.83 

3.70 

3.78 

11.17 

14.95 

1!7       1     4.11 

12    7 

n  ii.d 

•J«      1    4,  :i 

12  U 

14    3.3 

:iii      I    0. 1 

i:i    .■! 

14    8.1 

.Mfllll  Mil  1'.'.' 

ll.iglitnrCli'ViIili 

) ! 

14.8110 
.0.-.7 

> 

r 

14.  501 

( ■  .  022) 

) 

I 

tl   IllilllCi 

1"  ri'l'f  ri'iHi 

aliovt)  Tort  Colbnnui  loek- 

.ill- 

1H58 

..     14.800     .t.057    1 

1  MI'i 

..     14.50 

±.022 

. .       0. 23 

)    ±.00 

Tlie  zero  of  gage  at  Port  Colborne,  being  submerged  iiiasoury,  i.s  of 
iiiiqne.'^tioned  .stability.  The  canal  was  constructed  in  1S33,  and  if  any 
fit'ttliiig  followed  coii.strnctioii  it  was  doulitless  coiiiplote  bel'Ore  LS.jS; 
but  the  appearance  of  the  inasoni'y  above  the  water  gives  no  sugges- 
tion of  yielding. 

Tlie  earlier  v.-ork  at  Cleveland  was  connected  with  several  beiuih 
inailis,  all  of  which  have  been  ilestroyed,  but  before  the  disaiipeaiance 
of  the  last  one  the  datum  was  transferred  by  leveling  to  otliei'  points, 
Tlie  chain  on  which  the  record  deiiends  is  as  follows: 

1.  "Top  of  coi)ing  of  the  northeast  wall  of  the  Ohio  Canal  lock  where 
it  Joins  tlie  river."  The  high  water  of  1<S.'!,S  was  directly  compared 
with  this  bench,  and  AVhittlcsey  states  that  it  is  G.30  feet  above  that 
high-water  plane.'  As  the  observations  in  IS-^-S  were  made  near  the 
lock,  and  as  AVhittlesey,  who  rejiorts  them,  was  a  civil  engineer  whose 
writings  show  that  he  appreciated  the  importance  of  preci.se  bench 
marks,  it  is  ]irol)able  that  the  observations  were  jiroperly  connected 
with  (he  bench.  Explicit  statement,  however,  is  lacking;  the  record 
merely  refers  the  lake  level  to  the  high  water  of  1,S;5.S.  The  bench  was 
destroyed  in  1877  or  1878. 


1  ('11011(111111  Xnliinilist,  Vnl.  VII.  187.1,  p.  412. 


OII.HEKT.I 


PORT  COLHORNK  AND  ('LKVEI.AND  STATIONS. 


IV23 


2.  "Cross  on  water  table,  nortlieast  corner  of  .lolmsoii  House  block, 
southwest  corner  of  Front  and  Mast  liiver  streets."  On  .lime  )'>,  1S75 
(as  sliown  by  niiinns(n'ii)t  records  in  tlu- oHieeot'the  ('liiet'ot'  l"-ngincers, 
U.  S.  A.),  Assistant  ICngineer  T.  "\V.  Wri<;lit,  I'nitetl  States  Lake  Sur- 
vey, leveled  from  fliis  bendi  nuirk  to  the  canal  lock  copinn'  (1).  (indinjj 
tlie  diliercuice  (1  above  L')  to  be  .'[.(IT  feet.  This  bench  mark  is  still  in 
existence.  The  walla  of  the  building  are  cracl;  'd  in  such  manner  as  to 
indicate  some  settling  of  the  northeast  corner,  and  the  broad  llagstoiio 
on  which  the  bench  is  marked  stands  (in  1SK7)  (t.Ot  foot  lower  tlian  the 
next  stone  of  the  water  table  toward  the  west.  As  the  lower  stone 
supports  part  of  the  building  and  the  higher  stone  cari'ies  no  load, 
the  latter  maybe  assumed  to  show  the  original  level  of  the  former.  It 
is  impossible  to  say  whether  this  settling  atVeets  the  record  of  water 
levels.  The  building  was  erected  iu  1812,  and  istherelbre  ,'),">  years  old; 
it  was  :V.i  years  old  in  1875  when  the  datum  of  levels  was  transferred  to 
it.  The  datum  remained  with  it  eighteen  years,  until  ISIKS.  If  settling 
has  jirogressed  at  a  uniform  rate,  the  datum  was  affected  (»,(i  ■ ".  foot,  but 
it  is  e(|ually  possible  that  the  settling  belonged  to  the  early  history  of 
the  building  and  that  a  condition  of  practical  stability  was  reached 
prior  to  1.S7."). 

;{.  "  ISoltom  of  west  angle  iron,  on  bottom  of  ncu'th  longitudinal  jdate 
girder,  middle  of  first  full  depth  bent,  close  to  stone  pier,  new  L.  S.  v\:  .M. 
S.  It.  K.  drawbridge,  now  [1S9.'5]  being  finished. "  As  the  briflge  is 
symmetric  and  reversible,  this  description  applies  to  two  dilferent 
points,  but  measurement  shows  that  they  have  the  same  height.  It 
was  copied  from  manuscrii)t  records  iu  the  I'niteil  States  ICngineers 
oBice  at  Cleveland,  courteously  placed  at  my  servicer  by  Col.  .Tared  A. 
Smith.  The  records  show  that  in  .Tune,  IS'J.'J,  the  bridge  bench  (.'!;  was 
connected  by  leveling  with  the  .Tohnson  IFouse  bench  (2)  aiul  also  with 
the  gage  zero,  and  that  the  gage  zero  was  checked  by  the  bridge  in  ISilG 
and  found  correct.  The  gage  readings  in  IS!*")  (used  iu  our  comiiuta- 
tions)  are  thus  referreil  to  the  bridge  bench.  Thelieight  of  the  bridge 
bench  is  given  as  l.'.H  feet  above  the  "plane  of  reference."  and  by 
implication  as  1.71  feet  above  the  .lohnsou  House  bench  (2).  The  draw- 
bridge rests  on  a  stone  pier  many  years  older  than  tlie  present  bridge, 
and  there  can  b(^  little  (|uestiou  of  ils  stability. 

In  these  re(!ords  of  bench  marks  and  levelings  in  Cleveland  there  is 
certainly  much  to  be  desired,  bur.  the  ]iiesumption  is  nevertheless  in 
fii\or  of  good  work. 

It  api)ears  from  the  eomjiutation  that  the  ground  at  Port  Colliorne 
has  risen,  as  compared  to  the  ground  at  Cleveland,  (),2.>!»  foot,  or  about 
2;  inches  in  thirty-seven  years.  The  probable  error  of  this  nieasure- 
nu'ut,  as  indicated  by  the  discordance  of  gage  data,  is  three-fourths  of 
an  inch. 

Asa  check  upon  this  result,  a  third  computation  was  made  from  gage 
readings  iu  the  summer  of  1S72,  a  year  in  which  the  gage  zero  at  Cieve- 


V: 


624 


EARTH    MOVEMKNT   I\   THE    (iUKAT    LAKES    UEfilON. 


liiiiil  WHS  roiiiiccicd  with  tlie  ciiimllork  bi'iicli  iiiaik  by  instruiiu'iital 
Icvcliii;;-.  That  c.piniiiitatioii  j;ivi's  tor  the  hi'i-;ht  of  the  ])laiie  of  refer- 
(•net'  at  ('Icvchiiid  ahovf  tl,.-  lock  sill  at  Port  Collionu'  11.711  fi-et.  If 
wo  assunif  a  j;ra(liial  ciiaiif'*'  IVoiii  is.js  to  IS!ir>,  and  Interpolate  between 
1  l.sttO  feet,  tiie  (leterniinatioii  lor  IS.'iS,  and  1  l..')(il,  the  determinatioTi 
for  iS!»."),  wo  obtain  for  the  snninier  of  1.S72  the  value  1-1.710  feet,  which 
dillers  from  the  result  of  that  year's  observations  by  only  (MHt-l  foot.  The 
observations  on  Lak<!  Erie  thus  accord  well  with  the  theory  of  a  pro- 
grossivo  southward  tiltinj;'  of  the  land. 

The  Port  Colborne  ^afro  is  not  so  related  to  streams  as  to  subject  its 
readings  to  error  from  lloods.  The  Cleveland  j;ane,  like  the  Charlotte, 
is  on  a  river  estnaiy,  and  the  readiiifis  arc  subject  to  inlluoncc!  by  lloods. 
The  records  inclnde  no  systematic  account  of  the  condition  of  the  river, 
and  it  is  therefore  possible  that  some  of  the  observations  were  made 
when  the  river  level  was  above  the  lake  level. 


PORT  AUSTIN  AND  MILWAUKEE. 

At  eaidi  of  these  stations  autonnitic  gages  were  maintained  for  sev- 
eral years,  and  their  tracings  give  the  height  of  watei'  level  with  an 
amount  of  detail  [)ernutting  the  complete  eliniiinition  of  seiches  and 
tides;  but  there  was,  unfortunately,  some  uncertainty  as  to  the  iiosi- 
tion  of  the  zeros,  and  the  danger  of  thus  introducing  constant  errors 
led  me  to  avoid  the  automatic  records  an<l  clioosi;  times  when  other 
gages  were  emiiloyed.  The  earlier  period  selected  for  the  eoniinrison 
was  the  summer  of  ISTO,  and  the  gages  then  used  were  tloats  canying 
graduated  vertical  rods.  The  force  and  direction  of  the  wind  wore 
recorded  at  Port  Austin  by  this  gage  observer,  and  at  Milwaukee  by 
the  I'nited  States  Weather  ISurean.  From  an  in-;pection  of  these 
records,  together  with  the  Weather  Hureau  record-',  of  barometrii;  gra- 
dient, selection  was  nnide  of  the  jieriods  July  11  to  1!)  ami  August  l(i 
to  l!4,  excepting  oidy  certain  hoirs  when  the  force  of  the  hical  wind 
was  recorded  as  greater  than  .'i  in  a  scale  of  10.  This  gave  4(i  separate 
comparisons,  from  which  the  dili'orenco  in  height  of  the  gage  zeros  was 
comi)uted.  The  chosen  periods  are  well  disposed  with  reference  to  tides. 
The  readings  at  Milwaukee  were  made  at  7  a.  m..  1  p.  in.,  and  (!  p.  m., 
by  Mr.  John  .AleCabe;  at  Port  Ausiiu  the  hours  were  7  a,  m.,  H  p.  m..  ami 
9  p.  m.,  and  the  observer  was  Jlr.  J.  W.  Kimball.  In  the  computations 
the  midday  observations,  though  one  hour  apart,  and  the  evening 
observations,  though  three  hours  ajiart,  were  treated  as  simultaneous. 


PORT   AUSTIN   AND    MII.WArKKK   STATIONS. 


625 


Compiilalioii  of  heUjht  of  rjaiic  :erii  iil  I'nrl  Austin,  Micliiiinn.  nhiire  <iii;ie  ,-.)■»  nl   Mil- 
icaitktr,   IliHiiiiinhi,  in  Ihr  siimmrr  (if  /,V7r;. 


T'lilc. 

llcaillnKM 

Ill  Mil" 

■  iiUi-i'. 

K<'iiiliiiUH 

at  ri.rl 

.Vu^iiii. 

[>ifrtTillri 

7h.  m.    1 
Feel. 

1 1>.  m. 

Feet. 

0  ]i.  m. 

Ferl. 

7  a.  ni. 

Fret. 

'i  p.  III. 
Fret. 

U  |i.  in. 
F.rl. 

Fe.l. 

IHTt! 

Feet. 

! 

Feel. 

July     11 

2.17  1 

2.  23 

2.  12 

7.  22 

7.31 

7.47 

5.  05 

5.  OH 

5.  35 

12 

2.  12 

2.  03 

2.  II! 

7.51 

7.  25 

7.  22 

5.  42 

5.  22 

5.  (Ml 

13 

2. 20 

2.  05 

2.  35 

7. 35 

7.37 

7,  35 

5.  15 

5.  32 

5.  III! 

14 

1.  i»5 

2.  12 

2.  10 

7.  50 

7.41 

7.30 

5.  .55 

5.  29 

5.20 

15 

2.  Iti 

2.  15 

2.  lit! 

7. 33 

7.  35 

7.  ,30 

5.  17 

5.  20 

.5.21 

111 

2.  13 

2. 12 

2.  11 

7.31 

7.  25 

7.40 

.5.  21 

.5.  13 

5.  20 

17 

2.15 

2.20 

2.21 

7.37 

7.37 

7.30 

5. 22 

.5.17 

5.  (I!l 

18 

2.20 

2.07 

2.  20 

7.21   ■ 

7.25 

7.28 

5. 01 

5.  18 

5.  US 

in 

2.18    . 

7.31 

5.  It! 

All}.-.    Iti 

2.29    . 

2.  20 

7.  .50 

[■■;:35- 

,-).  21 

5.  15 

!7 

-'.  Ill    . 

2.21 

7.  33 

'    7. 50 

5.  14 

5.  20 

18 

2.23 

2.02 

2.27 

7.  50 

7.35 

7.40 

5.27 

5.  33 

5.  13 

19 

2.  ''2 

7.  45 

5.  23 

L'O 

2.18 

2. 23 

7.  (.2 

1 .  3i 

5.  4  1 

5.  1  1 

''1 

2.  25 

2.20 

2.  21 

7.41 

7.  :!4 

7.37 

5, 10 

5.  1 1 

5.13 

22 

2. 32 

2. 1« 

2.  33 

7.3X 

7.51 

7.  10 

5, 11(1 

5.  33 

5.  ( 17 

23 

2. 2(1 

l.'Jl 

2. 10 

7.38 

7.  fiO 

7.  .50 

5.  12 

5. 1)0 

5.  10 

I'l 

2.25    . 

2.  42 

7.4!l 

7.40' 

5.21 

5.  07 

.M<Mii 

1 

5.210 
:i.(ll3 

1 

111  LSIMl  the  gaga  at  Milwaukee  consisted  of  a  graduated  rod  held  in 
the  ob.server's  hand  in  nieasnriiin  down  to  the  water  from  a  fixed  point 
or  zero.  At  Tort  Au.stin  a  board,  carrying  a  graduated  scale,  was 
spiked  to  the  side  of  a  timber  crib,  and  the  position  of  the  water  sur- 
face on  the  scale  was  noted  by  the  observer.  At  each  of  these  stations 
a  series  of  12  ob.servations,  at  liveniinute  intervals,  was  made  every 
morning  and  evening  when  the  surface  of  the  water  was  iienrly  .smooth. 
The  mean  of  a  .series  was  afterwards  tieated  as  one  observation,  and 
the  coinputatioii  was  based  on  the  simultaneous  ])airs  of  observations — 
53  in  number.  The  selection  of  times  was  thus  determined  by  coii- 
ditioiis  favorable  for  the  elimination  of  seiehos,  but  it  aiipears  by  inspec- 
tion that  tidal  iutiuences  also  are  very  nearly  eliiniuated.  The  observers 
were:  At  Milwaukee,  Mr.  John  McCabe;  at  Port  Au.stin,  Mr.  John  P. 
Smith, 

As  the  zero  at  Milwaukee  was  above  the  water,  and  the  zero  at  Port 
Austin  below,  the  sum  of  the  readings  gives  the  height  of  one  zero 
above  the  other. 

18  GEOL,  PT  2 40 


62G    KAHTH  MOVEMENT  IN  THE  OREAT  LAKES  REGION. 

Co,nin.U,Uo„  ,,f  hcHM  of  rjage  :a;,  „i  Mihra.k-e,  in..o„Hl„    oho,r  „a,j. 


(ir  :ero  at    Port 


AiiKlin.   MUliiiiiiii,   in  'hi-  xummer  of  ISHU 


lieiiilini!" 

1 

Date. 

Tim*.    ' 

^!ihviiul^^■l■. 

1 
FrU. 

n.  ."i'.'8 

I'lirl 

Sum.      1 

1896. 

.Inly    20 

A.  M. 

1.271 

(i.  7!K) 

-'•I 

A.  M. 

'  .">.  is;i 

Lira 

ti.Hlli 

■M 

A.  M. 

.-..  70.'t 

1. 3X5 

7.088 

29 

A.  M. 
1'.  M. 

.-|.  170 

1.3.51 
1.375 

I!.  824 
6.935     j 

Aug.   1 ; 
^1 

A.  M. 
1'.  M. 

5. 1120 

1.2!'7 
1.125 

(i.733    j 
7.015     i 

7 

1'.  M. 

").  117 

1.  120 

6.^07 

'J 

A.  M. 

.-...-,  19 

l.ilS 

0. 907 

11 

A.  M. 

.">.  ."i7."> 

1.  133 

7.008    j 

14 

A.  M. 

5.  :w8 

1.  455 

0.793    1 

20  ' 

A.  •■. 

5.  .•>87 

1.310 

0. 927 

20 

I'.  y\. 

5. 571 

1. 40() 

fi.977 

21 

A.  M. 

5.  .-|.-)S 

1.330 

6. 888 

1'.  M. 

5.  .".X« 

1.391 

ti.  979 

22 ; 

A.  M. 

5.  .")()5 

1.2,V.l 

6.701 

1'.  M. 

5.  5 10 

1.22!l 

6.  769 

21 

1'.  M. 

5.  .")9."> 

1.375 

6. 970 

2,"> 

A.  M. 

5.721 

1.221 

6.912 

25 

1'.  M. 

5. 792 

1.  21 W 

7.000 

28 

P.M. 

5.721 

1 .  271) 

7.000 

30 

V.  M. 

5.  7!I7 

1.239 

7.036 

Sept.     1 
2 

P.  M. 
P.  M. 

5. 725 
5.  74X 

1.259 
1.2113 

6.984 
6. 951 

4 

P.  M. 

5.  720 

1.2  IS 

6. 968     i 

5 

P.M. 

5.515 

1.134 

6.  649 

7 

P.  M. 

5.  7;i!l 

1.275 

7.014 

8 

A.M. 

5.  t)49 

1.203 

6. 8.52 

P.M. 

5. 595 

1. 139 

6. 734 

9 

P.  M. 

5.  5K5 

1.077 

6. 662 

14 

A.M. 

5.5S-1 

1.208 

6.  792 

15 

A.M. 

5.  .500 

1.181 

6.  74 1 

20 

P.  M. 

5. 892 

1         1.2H1 

7.173 

23 

A.M. 

5.791 

1         1.307 

7.098 

25 

A.  M. 

5.932 

!        0. 803 

6. 735 

28 

P.  M. 

5.755 

1.167 

6.922 

29 

A.  M. 

5.615 

I.OIJ 

6.628 

I 


POKT   AUSTIN    AND    MILWAL'KEK    STATrONH. 


627 


Computation  of  liiiijlil  of  ijui/e  :eio  at  Milirmdrr,    ll'idiiiiiHiii,  abuie  ijiigu  :eri,  nl  I'ort 
AitHlin.  Miiliii/aii,  in  the  kiiiiiiiipi-  ni'  /,<l:ii:—i'iit\Uu\itu\. 


fturleii). 


Dati'. 


8nin. 


IMUwaiikee. 


Port 


18!l«.        ' 

Feel. 

Feel. 

Feel. 

Oct.       2 

A. 

M. 

->.  5t)« 

1.  2.50 

(!.  Hlli 

3  t 

A 

M. 

5. 594 

i.4a5 

7.  0.5!l 

1 

P. 

M. 

5.574 

1.1«6 

t'l.  7liO 

1 

P. 

M. 

r,.  ()3L> 

1. 101 

(i.  73H 

5 

1'. 

M. 

5.  705 

1.0H5 

(!.  7!tO 

10 

P. 

M. 

5.  50(i 

0.  8«» 

ti.  3!  15 

ir. 

A. 

M. 

5.  781 

0. 7t>9 

•  6. 553 

17 

A 

M. 

5.  VA2 

1,  144 

7.0«fl 

IX 

A 

M. 

5.  720 

1,  3!W 

7.11H 

1!( 

A. 

>[. 

5.  SKi 

1.215 

7.0t!l 

''li 

A. 

M. 

fi.  1m:! 

1.212 

7.;«ti 

:'"> 

A 

M. 

li.  Hi!) 

0. 800 

(i.  !t3!l 

26 

P. 

M. 

5.!  Kill 

0.  «58 

11.  SIS 

L'7 

A. 

M. 

5.  ni« 

0.  7.50 

(i.  i'A'iH 

P. 

M. 

5.  MOO 

0.  722 

(1.531 

l''J 

A. 
II 

.M. 

5.  XBl 

0.  724 

1 

(1.  5f>!S 

Jlci 

G.875 

I 

±.  019 

iiaiks,  and  it  i.s 


Milwaukee  is  well  provided  with  enjjineer  beiicli 
probable  that  thorough  research  would  establish  tiie  coiiiii'i^tioii  of  tiie 
gage  zeros  at  eaeh  oiiocli  with  several  of  the  bench  marks;  but  after 
iuspeetiou  of  the  data  readily  accessible,  I  thought  it  best  to  make  u.se 
of  only  one  bench,  that  called  the  '■  check  jjoint."  This  consi.-^ts  of  the 
toi»  of  a  copi)er  bolt  leaded  into  the  north  side  of  the  center  ))ier  of 
the  swing  bridge  over  the  river  between  Chestnut  and  Division  streets. 
The  gage  observer  is  refjuired  at  stated  intervals  to  check  the  stability 
of  the  zero  of  liis  gage  by  means  of  this  check  point.  Using  two  rods, 
with  the  aid  of  an  assistant  he  makes  a  series  of  simultaneous  meas- 
urements from  the  check  jjoint  and  from  the  gage  zero  down  to  the 
water  level,  and  from  these  measurements  the  relation  of  the  gage 
zero  to  the  check  point  is  determined.  Their  relation  has  also  been 
determined  by  means  of  the  engineer's  level  at  various  times,  and 
was  so  determined  on  August  8,  1876,  by  Assistant  Engineer  L.  L. 
Wheeler,  who  found  the  check  iioint  0.843  foot  above  the  gage  zero, 
lu  1890  the  check  observations  by  the  observer  were  very  thorough, 
series  of  twenty  simultaneous  readings  being  made  every  fortnight, 


m 


628    EARTH  MOVEMENT  IN  THE  GREAT  LAKES  REGION. 

and  from  five  of  tbeso  series  tlie  relation  of  the  two  points  is  computed 
as  follows: 

Coinpiitdtion  of  hdiiht  of  Milwdtdre  check  poiiit  aboi-r  Milwaiihef  -no  of  gage  in  the 

mtmmer  of  lSHi:. 

I-'i-i't. 

Julv  1-'  iiiu'iiu  (if  twenty  coiiipiirisiins  bv  siiriultaiicoiis  readings) l.L'0;{ 

July-i; I I-^l^ 

Anj;iist  11 l--'^f 

A 11 K 1 1 » t  L'  X 1  ■  2t« 

ye)iti'nilpiT  16 l--Ot) 

Mran 1-^1'^ 

i.0(l2 

In  response  to  a  letter  of  in<iairy  as  to  the  stiibility  of  the  Milwaukee 
check  point,  Ciipt.  (teorjre  A.  Zitin,  United  States  engineer  in  charge 
of  liarbor  improvements,  writes  as  follows : 

The  Chestnut  Street  Hridt'e,  on  the  center  jiier  of  which  the  chock  point  ia  estab- 
lished, was  liiiilt  in  1871.'. 

.Mr.  (J.  H.  liouzenlierg,  city  engineer,  states  thut  the  pier  rests  on  a  ])ile  founila- 
tioii;  that  ti)  liis  liiiiiwlcdfie  the  drawbridge  lias  iisviT  bei'ii  releveled  since  put  in 
place,  and  that  if  any  appreciable  settlement  had  taken  jilace  in  the  center  jiier  it 
would  liavo  iiitcrfeied  witli  the  opeiatiiij;  of  the  swing  bridge.  Ho  stated  jiosi- 
tively  that  no  settlement  had  occurred. 

The  principal  bench  mark  used  in  187()  at  J'ort  Austin,  called  the 
Wisncr  bench  mark,  was  a  copper  bolt  leaded  into  bed  rock;  but  in 
IS'.K!  1  was  unable  to  tind  it.  and,  as  at  Milwaukee,  I  had  recourse  to  a 
bench  mark  originally  established  and  used  as  a  check  point,  it  is  the 
toj)  of  an  iron  bolt  driven  into  a  vertical  face  of  bed  rock  on  thi!  west 
side  of  a  promontory  opposite  the  residence  of  Mr.  .1.  W.  Kind)all.  In 
July,  1S7.">,  and  October,  187<i,  Assistant  l']ngincer  T.  W.  Wri^jht  found 
the  check  point  T.-i-tfeet  below  the  Wisner  bcnttli  mark;  in  June.  IS90, 
I  found  the  gage  zero  5.1'J.j  feet  below  the  check  point,  this  (iiuxntity 
being  the  mean  of  two  measurements. 

^lanuscript  records  in  the  archives  of  the  Lake  Survey  state  that  the 
Port  Austin  gage  zero  was  originally  placed  on  a  level  with  the  Wisner 
bench  mark,  but  that  in  July,  1875,  it  was  O.OO.'J  loot  too  low,  and  that 
on  October  18,  ]87(i,  it  was  ().(t40  foot  too  low,  having  settled  during  the 
interval.  As  the  observations  used  fall  within  this  interval,  it  wiis 
necessary  to  make  some  assumption  in  regard  to  this  s*>itling,  and  the 
assumption  made  was  that  it  had  been  at  nnirorm  rate  through  the 
whole  period.  The  corre<!tion  interpolated  for  the  time  of  observati(»ii 
was  0.(i8t  loot.  Combining  this  correction  with  data  from  leveling  in 
1875  and  187(>,  I  obtained  as  the  height  of  the  gage  zero  above  the 
clieck  point  in  July  ami  August,  1870,  7.4()()  feet.  T'>e  various  data 
thus  described  are  combined  in  the  foUowiug  table. 


•  1    ( 


PORT   AUSTIN   AND    MILWAUKEE   STATIONS. 


G29 


Compiiiation  of  height  of  Milwaukee  check  point  ahoie  Port  .tiialin  chcfl,  point  in    the 
mimmern  »/'  ISTH  iind  !S9C. 


1870. 


Feet. 
1.205 
fi.S75 

— .-|.  125 


!  Feel. 

Milwaukee  check  point  above  Milwaukeo  gage  zero :  0.  Hi;i 

Milwaukee  gage  zero  above  Port  Austin  gage  zero ■  — 5.  210 

Port  Austin  gage  zero  above  Port  Austin  oheik  point 7. 4tiO 

Sum  of  above  =  Milwaukee  check   jioint  iibove  Port 

Austin  check  point 3.(l'J:i 

Difference — i).  138 


This  result  iudicate.s  that  the  grouud  at  Milwaukee,  as  cDinpared  to  the 
ground  at  Port  Austin,  has  subsided  0.138  foot  in  the  twenty  years  from 
1876  to  1890.  It  is  the  algebraic  sum  of  six  measurements,  of  which 
three  are  levelings  by  water  surface  and  three  by  the  engineer's  level. 
The  probable  errors  of  the  water-level  measurements  are  1;  0.010,  ±  0.013, 
and  ±0.002.  The  probable  errors  of  the  Port  Austin  levelings  in  1890, 
as  indicated  by  the  discordance  of  two  independent  results,  is  1:0.008. 
If  the  probable  error  of  each  of  the  other  measurements  was  ±0.(I10, 
the  probfible  error  of  the  result  is  less  than  J  .03  foot.  There  is 
also  an  uncertainty  arising  from  the  possibility  that  the  stone  pier  to 
which  the  Milwaukee  check  mark  is  attached  has  settled,  another  uncer- 
tainty dne  to  the  possibility  of  river  floods,  and  a  third  involvt'<l  in  the 
assumption  that  the  settling  of  the  Port  Austin  gage  zero  in  1870  was 
at  a  uiiitbrin  rate.  If  all  the  settling  of  the  Port  Austin  zero  took  i)lace 
before  the  i)eriod  of  observation,  the  assumptiou  makes  the  result  too 
large  by  0.000  foot;  if  all  the  settling  took  place  after  the  observations, 
the  assumption  makes  the  result  too  small  by  0.031  foot.  The  Port 
Austin  record  is  free  from  stream-flood  influences,  but  tlie  .Milwaukee 
gage  station  is  ou  a  narrow  estuary,  like  the  stations  at  Charlotte  and 
Cleveland. 

ESCANABA  AND  MILWAUKEE. 

In  ('omi)aring  E.scauaba  with  Milwaukee  the  sani<'  general  periods  of 
observation  were  employed  as  in  comparing  Port  Austin  with  Mil- 
waukee, but  the  individual  days,  though  selected  in  the  same  manner, 
were  in  i)art  different.  Filty-one  separate  comparisons  were  made  in 
1876,  and  52  in  1890.  The  selection  of  times  was  controlled  by  condi 
tions  favorable  for  the  elimination  of  seiches,  but  the  combination  of 
days  chosen  was  found  to  approximately  eliminate  tidal  elfects  also. 

The  observations  at  ICscanaba  in  1870  were  conducted  in  the  same 
manner  as  at  Milwaukee  and  Port  Austin,  the  h(mrs  being  7  a.  m.,  2 
p.  m.,  and  !•  p.  ni.,  and  the  observer  Mr.  George  Preston.  In  1890  tha 
system  was  the  same  as  at  Milwaukee,  the  observer  being  Mr.  Clinton 


■m 
■■ll 

II 


630 


EAETH   MOVEMENT   IX    THE    GREAT   LAKES   REGION. 


V|> 


B.  Oliver.    Tlie  following  tables  give  tbe  coinput.ations  for  the  two 
year.s : 

Computation   of  height   of  (jaije   zero  nl    Miliidiikee,     ll'iscoiiain,   dboie   gaije  ziro    at 
J.'aviinabu,  Mivhiijan,  in  the  isiimmir  of  IS^H. 


Date. 

liead 

ngs  nt  EKCnnaba. 

.  Iteadiiigs  at  Milwaukee. 

7  A.  m. 

2  p.  m. 

9  Jl.  III. 

7  a.  111. 

t 

1  p.  ni. 

0  p.  III. 

1876. 

Feel. 

Fett. 

Feet. 

Feel. 

Fett. 

Feet. 

Feet. 

Feet. 

j      Feet. 

July    11 

1.86 

1.90 

1.78 

2.17 

2.23 

2.12 

0.31 

0.33 

'  0.34 

12 

l.ilO 

1.75 

1.78 

■    2.12 

2.03 

2.16 

.22 

.28 

..S8 

13 

2.00 

2.07 

1.95 

2.20 

2.05 

2.35 

.20 

—.02 

.40 

14 

2.10 

2. 15 

2. 05 

1.95 

2.12 

2.10 

—.15 

—.03 

.05 

15 

1.!I6 

1.95 

2.00 

2.16 

2.15 

2.06 

.20 

.20 

.06 

16 

1.90 

1.95 

1.85 

2.13 

2.12 

2.11 

.23 

.17 

.26 

17 

1.89 

1.80 

1.85 

2. 15 

2.  20 

2.21 

.26 

.40 

.36 

18 

2. 0,5 

1.85 

1.95 

2.20 

2.07 

2.20 

.15 

.22 

.25 

1!1 
Aug.   16 

1. 7.5 
2.07 

1.94 



1.90 

2.18 
2.29 

2.30 

2.20 

.43 
.22 

.36 

.30 

17 

2.00 

1.95 

1.  95 

2.19 

2.13 

2.21  1 

.19 

.18 

.26 

18 

1.70 

1.9.S 

2.00 

2.23 

2.02  , 

2.27 

.53 

.09 

.27 

19 

1.78 

2.00 

2.13 

2.22 

.35 

.22    

20 

1.95 

1.90 

1.85 

2.23 

2. 18  1 

2.23 

.28 

.28 

.38      1 

21 

1.85 

2.05 

2.10 

2.25 

2.20      2.24 

.40 

.15 

.14 

22 

1.83 

2.05 

1.90  1 

2.32 

2.18       2.33 

.49 

.13 

.43 

23 

1.91  1 

1.83 

1.75 

2.20 

1.91  '    2.10 

.35 

.08 

.35 

24 
Men 

1.95  1 
n 

1.85  1 

1.90 

2.25 

2. 10       2.  42  ! 

.30 

.25 

1 

.52 

0.  2,55 

■■■"1 

i.012 

«l  ( 


OltBKKT.] 


ESCANABA   AND   MILWAUKEE   STATIONS. 


631 


Computation  of  height  of  gage  zero  at  EKcanaha,  Michigan,  above  gage  zero  at  Mihiaulcee, 
Wisconsin,  in  the  summer  of  1896. 


Date. 

Time.    ' 

1 

KcniliD^^s  (means  of 
dericH). 

DilTcreiiie. 

Milwankeo. 

Gscaiinba. 

1896. 

1 

Feel. 

Feet. 

Feel. 

■July      2 

P.M. 

5.465 

5.917 

0.  452 

7 

A.M. 

5.434 

.-).907 

.473 

8 

A.M. 

5.505 

5.920 

.415 

9 

A.M. 

5.348 

5.837 

.489 

P.M. 

5.356 

5.7ft5 

.409 

10 

A.M. 

5.442 

5.771 

.  329 

P.M. 

5.567 

5. 694 

.127 

11 

P.M. 

5.576 

5.771 

.195 

13 

A.M. 

5.411 

5.869 

.458 

P.M. 

.5.493 

5.776 

.283 

14 

A.M. 

5.574 

5.750 

.176 

17 

A.M. 

5.431 

5.865 

.434 

19 

A.M. 

5. 524 

6.007 

.483 

P.M. 

5.496 

5.887 

.  391 

20 

A.M. 

5.528 

5.803 

.275 

21 

A.  M. 

5.573 

5.973 

.400    j 

23 

A.M. 

5.645 

5.908 

.263 

25 

A.M. 

5.601 

5.856 

.2,55 

28 

A.M. 

5.703 

5. 857 

.154 

31 

A.M. 

5.446 

5.938 

.492 

Ang.     1 

P.M. 

5.360 

5.859 

.499 

4 

A.M. 

5.654 

5.912 

.258 

8 

P.M. 

5.317 

5.954 

.607 

9 

A.M. 

5.519 

5.658 

.  139    1 

10 

P.M. 

6. 328 

5.546 

.218 

13 

A.M. 

5. 273 

'>.  616 

.  34!) 

P.M. 

5. 378 

5.  752 

.371 

14 

A.M. 

5. 338 

5.670 

.  332 

15 

A.M. 

5. 360 

5.  730 

.370 

P.M. 

5. 402 

5.  710 

.308 

19 

A.M. 

5.414 

5.878 

.464 

21 

A.M. 

5.558 

5.935 

.377 

P.M. 

5. 588 

5. 872 

.281 

22 

A.M. 

5.505 

5.698 

.183 

Sept.    4 

A.M. 

5.734 

6.028 

.294 

13 

P.M. 

5.452 

5.848 

.396    1 

14 

A.M. 

5.584 

6.762 

.178 

16 

A.M. 

,->.500 

5.937 

.437 

il « 


632 


EAKTH   MOVKMENT   IN   THE   GREAT   LAk'ES   REGION. 


Conumtation  of  height  of  gage  zero  at  Escanaba,  Michigan,  above  gage  sero  at  Milwaukee, 
Wisconsin,  in  the  summer  of  ISnC— Continued. 


])ate. 

Tinio. 

Headings  (moans  of 
«orit'B). 

Difference. 

Milwfiiikue. 

Ksi-anabn. 

1890. 

Feet. 

Fett. 

Feet. 

Sept.  18 

A.M. 

5.  701 

6.047 

.346 

L'6 

A.  M. 

,-).itU 

6.187 

.273 

28 

1'.  M. 

5.  I'm 

6. 224 

.469 

20 

P.  M. 

5. 510 

0. 133 

.623 

Oct.       7 

A.  M. 

-...-.M 

6.164 

.6150 

M 

A.M. 

.-..  731 

6. 270 

.539 

14 

P.M. 

5.813 

fi.157 

.344 

17 

P.  M. 

r<.  fi22 

C.  160 

.  .->38 

lit 

A.M. 

r,.  84r) 

6.  287 

.441     1 

20 

A.  M. 

.->.  8.^7 

<i.  346 

.489    j 

22 

A.  M. 

{).  182 

6.  r>;i!i 

..S.-.7    ' 

I'.  M. 

(i.  MX 

6.  .-)40 

.392     i 

26 

A.  .M. 

(!.  080 

(!.  471 

.  391 

P.  M. 

5.  i)80 

6.11 14 

..")6l 

Menn. 


0.  374 

;i-.012 


Tlie  bench  employed  at  Milwaukee  lias  already  been  described.  At 
Escanaba  there  were  three  bench  marks  in  good  standing',  as  follows: 
No.  1,  the  top  of  the  water  sill  on  the  southeast  corner  of  the  Adler 
building,  northwest  corner  of  Ludingtou  street  and  Drusemau  avenue; 
No.  '2,  the  top  of  the  water  sill  of  the  Escanaba  lighthouse  at  the  north 
side  of  front  dooi-,  against  the  brick  wall;  No.  .'i  is  described  in  1876 
as  the  "center  of  a  copper  bolt  set  horizontally  in  the  foundation  of  the 
light-house,  west  side,  north  corner,  A  feet  north  from  steps."  In  a 
description  by  Oapt.  (ieorge  A.  Zinn,  dated  -lune  liO,  ISOO,  tlie  top  of 
the  bolt  is  specified.  I  am  informed  by  Mr.  ( 'liiiton  H.  Oliver,  the  gage 
observer,  that  the  diameter  of  the  bolt  is  thiee  eighths  inch.  The  rela- 
tive heights  of  two  or  more  of  these  bench  marks  have  been  determined 
in  at  least  six  difterent  years,  the  inoasurements  being  made  independ- 
ently with  the  engineer's  level.  It  is  advantageous  to  compare  these 
nieisurements,  not  only  to  learn  what  confidence  is  to  be  reposed  in 
the  individual  benches,  but  for  the  sake  of  whatever  light  ipay  be  cast 
on  the  general  precision  of  such  data. 


■     ( 


ESCANAHA   AND    MILWAUKEE    S^TATIONS. 
Comparison  of  Encanaba  lieiich  marks  irith  one  anothir. 


633 


Tear. 


Above  zero  of  gage. 


Xo.  3. 


Ditlon'iice  bi'twvi: 
Ih'iii-1i  inarkH. 


Feet.     !    Feet.         Feet. 
2.100    a(i.23.-» 


Feel. 


Deviation  r'-<<iii  nn-iin. 


1  -3. 


2  —  3. 


Feel. 


Feel. 


Feel. 


Feel. 


1.302 
1.035 
1. 280 
1.283 


,">.477    1 +0.0(«  

.">.  405  fi.482  t  1.017   —  .0011  +0.001'     +0.(105 

5.476  a(!.K13  ial.  367    +  .002  

,").46«  0.473  !  1.005  —  .006  —  .011    —   .0117 

5.483  0.407     1.014    +  .OOil  +     013    +    .(1(12 


.Meiin 1 5.474     6.484  j  1.012 


aNiit  uHed  ii)  ('(iiiiputii)};  iiieanH- 

In  this  table  the  le.idiiiff  of  the  height  of  bench  Jiiavk  No.  .'5  in 
187(»  is  corrected  for  tlie  distance  between  centei'  and  top  f  Itolt.  In 
the  first  division  of  tlie  table  the  benches  are  reterred  to  zero  of  gage, 
but  as  the  gage  was  not  <!onstant  in  position  these  uiinibers  differ 
widely  from  year  to  year.  In  the  second  division  the  relations  of  the 
gages  one  to  another  are  given,  being  deduced  by  subtraction  from 
the  numbers  of  the  first  division,  and  the.se  figures  are  more  accord- 
ant. It  appears,  however,  that  the  dift'erence  between  benches  1  and  2 
ill  1874  departs  widely  from  differences  tunnd  in  other  years,  and  it  is 
therefore  probable  that  a  blunder  of  measurement  or  record  was  made  in 
that  year.  It  appears  further,  by  insi)ectioii,  that  the  difference  betweiMi 
benches  1  and  3  and  the  ditt'ereuce  between  benches  2  and  3  in  1880  are 
not  ill  accord  with  the  <liffereiices  found  in  otiier  years,  and  it  is  evi- 
dent that  some  blunder  was  made  in  the  nieasuremeiit  or  record  of  the 
height  of  bench  .'5  for  that  year.  These  figures  were  accordingly  thrown 
out  and  not  u.><ed  in  the  computation  of  the  means.  Tlio  numbers  of 
the  third  division  were  obtained  by  subtracting  the  means  from  the 
several  miinbers  of  the  .second  division,  and  they  show  the  deviations 
from  mean  after  reject  ing  the  records  showing  gross  errors.  Inspection 
of  the  table  of  deviations  shows  that  their  signs  are  irregularly 
distributed,  and  discovers  no  evidence  of  jjrogressive  change  from 
year  to  year.  It  is  therefore  jirobable  that  all  three  of  the  Ixuiches  are 
staide,  and  tliat  the  deviations  of  the  measiirenients  from  uniformity 
represent  oru:;iary  errors  of  oiiservation.  They  may  accordingly  be 
used  as  a  rough  measure  of  the  ])r«.'cisioii,  barring  blunders,  of  the 
instrumental  leveling  on  which  the  results  of  this  investigation  largely 
depend.  Their  mean  is  O.OOli  foot,  and  the  comp"*^^ed  probable  error  of 
a  single  measurement  is  ±0.008  f.iot.  In  comb  ig  various  data  for 
the  coin])arison  of  I']scanaba  with  Milwaukee,  bench  mark  No.  1  of 
Escauaba  Wiis  first  used. 


I.S 


«      ( 


634    EARTH  MOVEMENT  IN  THE  GREAT  LAKES  REGION. 

ComimUiHon  of  Ihe  height  of  Kscaimhi  bench  mark  Xo.  1  above  Milwaukee  checkpoint  in 
the  siimmviH  of  1S7(;  ami  ISM. 


1876. 

IBSe. 

Fret. 

Feet. 

7.87+ 

7.780 

— 0.2ri5 

.374 

— 0.X43 

— i.2or. 

Ksiiiniilia  lieiiili  No.  1  aliovc  Esciuiaba  ga>;o  zito 

Escauaba  (taKf  zero  j''   )Vc  Milwaukee  gai;e  zero 

Milwaukee  gaj,'e  iser      l-ore  Milwaukee  cheek  poiut  . . 

.•^uiu  of  aliove  =  E9canal)a  bench  Xo.  1  above  Milwaa- 
kee  check  point "•  T"" 

Difference +   •1''3 


I).  949 


The  result  iudicptes  that  the  ground  at  Escaiiaba,  as  compared  with 
the  ground  at  Milwaukee,  has  risen  0.173  '  .)t  in  twenty  years.  This 
quantity  is  tlie  algebraic  sum  of  six  measurements,  of  which  three  were 
made  through  water  leveling  and  three  by  instrumental  leveling.  The 
probable  errors  of  the  water  levelings  are  ±0.012,  iO.Oll',  and  ±0.002 
foot;  the  estimated  probable  error  of  the  instrumental  levelings  at 
Milwaukee  is  ±0.010  foot,  and  of  the  two  levelings  at  Escauabaeach 
± O.OOS  foot.    This  gives  as  the  probable  error  of  the  result  ± 0.022  foot. 

A  similar  computation,  using  bench  mark  No.  2  instead  of  bench 
mark  No.  1,  gives  0.155  foot  instead  of  0,173,  and  a  compution  based  on 
bench  mark  No.  3  gives  0.150.  The  mean  of  tlie  three  results  is  0.101 
foot,  with  a  probable  error  of  ±0.022  foot.  The  only  important  uncer- 
tainties to  which  this  result  is  subject,  besides  those  indicated  by  the 
discordance  of  meiisurements,  arise  from  the  possibility  of  the  settling 
of  the  bridge  pier  to  which  the  Jlilwaukee  check  point  is  attached  and 
the  possibility  of  ri\  er  floods. 

mSCBEl'ANCV  MOTED  BY   CAPTAIN  MARSHALL. 

In  the  later  work  of  the  United  States  Lake  Survey  all  determinations 
of  lake  level  were  referred  to  the  high-water  level  of  1838,  which  is 
called  the  "  plane  of  reference.''  That  plane  was  directly  observed  by 
Dr.  I.  A,  Lapliam,  the  geologist,  and  with  the  aid  of  a  bench  mark  on 
his  house  at  Milwaukee  was  permanently  recorded.  For  other  stations 
on  Lake  Michigiin-Huron  its  position  was  determined  by  assuming 
that  the  level  of  1838  had  everywhere  the  same  height  above  the  mean 
lake  level  as  determined  by  long  series  of  observations.  For  the  deter- 
mination of  this  plane  at  Esc<;naba  use  was  made  of  observations  for 
the  period  from  January  1, 18')0,  to  December  31, 1875.  In  1887  Capt. 
W.  L.  Marshall,  U.  S.  E,,  under  whose  direction  the  gage  readings  at 
Milwaukee  and  Escanaba  were  then  nmde,  detected  a  discrepiincy, 
which  he  reported  to  the  Chief  of  Engineers  in  a  letter  dated  October  1.' 


I  Ami.  liipt.  Chief  of  KnglnoerH,  U.  8.  A.,  for  1H87.  part  3,  p.  2417. 


_ 


■  I     i 


1  v^ 


SUMMARY    OP   KESULTK. 


635 


In  former  reporta  the  zero  of  Kscanalia  i^iijiB  has  been  assuiiiod  as  O.Tti  font  above  the 
piano  of  reference,  Imt  a  comparison  of  correctcil  readings  at  MihvaukceandKHCMualia 
shows  that  th<^  deterniinatious  of  tlie  plane  of  reference  at  Milwaukee  and  Kscanaba 
vary  0.187  foot,  the  Kseauaba  plane  bcintj  too  high  or  the  Milwaukee  determination 
too  low. 

In  the  light  of  present  knowledge  it  seems  i>robiible  that  the  dis- 
crepancy thus  noted  by  Captain  Marshall  as  au  error  was  occasioned 
either  wholly  or  in  chief  part  by  the  progressive  tilting  of  the  land. 
This  conclusion  isdirticult  of  verification,  because  little  record  survives 
of  such  checks  as  may  have  been  made  upon  the  heights  of  gage  zeros 
during  the  i)i'riod  1800-1875;  but  the  indicated  change  agrees  in  direc- 
tion, and  approximately  in  rate,  with  the  change  deduced  from  the 
present  investigation.  From  the  middle  of  the  period  1800-1875  to  the 
summer  of  1887  was  an  interval  of  twenty  years,  equal  to  the  interval 
1870-1890  here  used,  and  the  discrepancy  of  0.187  foot  discovered  by 
Captain  Marshall  differs  irom  the  change  of  0.101  foot  here  deduced 
by  a  quantity  little  greater  than  the  probable  error  ascribed  to  the 
latter  determination. 

SUJOIAUY  OF  RESULTS. 

In  the  following  table  are  assembled  the  numerical  results  as  to 
changes  in  relative  height  of  the  four  pairs  of  stations.  Besides  the 
measured  changes,  the  table  includes  the  periods  intervening  between 
dates  of  measurement  and  distances  between  the  stations  of  each  pair. 
The  lines  connecting  pairs  of  stations  have  a  southwesterly  direction 
(fig.  !>!•,  p.  013),  and  it  is  the  northeastern  station  of  each  pair  that 
appears  to  have  risen  as  compared  to  the  other. 

The  results  thus  show  a  general  agreement  with  the  working  hypoth- 
esis, that  the  latest  change  recorded  by  geologic  data  is  still  in  progress. 
To  make  the  comparison  quantitative  there  should  be  substituted  for 
the  direct  distances  between  stations  the  corresponding  distances  in 
the  assumed  direction  of  tilting,  S.  27°  \V.,  and  the  measured  results 
for  various  distances  and  various  time  intervals  should  be  reduced  to 
a  common  basis.  Ju  the  third  column  of  the  table  are  the  reduced 
distances,  and  in  the  sixth  the  reduced  r  ites  of  change.  Assuming 
the  change  to  have  a  uniform  rate  and  to  be  the  same  for  all  parts 
of  the  region,  the  measurements  at  the  dflerent  pairs  of  stations  give 
for  a  distance  of  100  miles  and  a  period  of  a  century  the  iwantities  of 
the  sixth  column.  The  seventh  column  coni^ins  the  probable  errors 
of  quantities  in  the  sixth,  and  is  based  on  the  jirobable  errors  of  the 
measured  changes  iu  pairs  of  stations. 


.A\ 


I , 


■fl-c 


G30  KAIiTII    MOVEMENT   IN   THE    GREAT   LAKES   REGION. 

Sumtnari/  <)/  ilinl,iiiaH,  time  iiilcrritU,  ami  mvamirdninlH  of  tUffircnlial  enrlli  mortmciilt. 


,,      ,    '^''-'-o'lr;:™:    Change 
„,,..,Hure.      ,„„^„, 


iliHtani'f.        tjon 


I 


Sacki'tts  Harbor  iiiiil 
I        t:harlotte 

Port  Coll)ornc  and 
!        Cleveland 

I'ort  Austin  and  >Iil- 

wankee 

I     liscanalia     and    Mil- 


llilfi.    I    mU:    I    Years.    |      Feet. 
•J2 


88  76 

ir.s   j     111 

259  17(i 


Feel. 


Feet. 


0.061  0.37  j      0.18 

0.2.30  0.46  0.11 

.'0        0.137  I    0.39  0.09 

.'0         0.161  0.  r!  0.06 


wankce 192  180 

Mean 0.  II 


Weiglited mean 0.42    ,  ±0.044 


I.S  TlIK  LAXI)  tiltixg:' 

With  the  iiuiuericiil  results  of  the  investigation  before  »s  we  may 
now  recur  to  the  main  subject  and  ask  whether  the  evidence  warrants 
the  condusion  that  a  general,  gradual  tilting  of  the  basin  is  in  prog- 
ress. In  the  discussion  of  the  data  used  in  coini)aring  the  several 
pairs  of  stations  it  has  been  found  that,  taken  at  their  face  value,  tlioy 
indicate  a  tilting  in  the  hypothetic  direction,  but  it  has  also  been 
fouiul  impossible  to  resolve  all  doubts  as  to  the  stability  of  the  gages 
and  benches  and  the  accuracy  of  the  measurements.  By  reason  of  these 
doubts  the  result  from  no  single  pair  of  stations  is  conclusive,  but  when 
assembled  they  exhibit  a  harmony  which  argues  strongly  for  their 
validity.  As  tabulated,  there  are  four  results,  but  these  are  not  all 
independent,  since  ol)servations  and  measurements  at  Milwaukee  are 
used  twice.  There  are,  however,  three  results  wholly  indeiiendent  and 
a  fourth  partly  independent.  To  these  may  be  added  a  fifth  nartly 
indei)eiHlent,  namely,  the  determination  of  change  between  I^ort  Col- 
borne  and  Cleveland  for  the  shorter  period,  1872-1895.  Not  only  do  all 
these  results  indicate  a  change  of  the  same  sort,  but  they  agree  fairly 
well  as  to  quautity.  The  computed  change  for  100  miles  in  a  century 
ranges  only  from  0.37  to  0.46  foot,  and  the  greatest  deviation  of  an 
individual  result  from  the  mean  of  four  is  12  i)er  cent.  This  measure 
of  harmony  appeals  strongly  to  the  judgment,  and  is  also  susceptible  of 
appro.xiinate  numerical  expression.  If  the  four  determinations  tabu- 
lated in  the  sixth  column  are,  in  fact,  measures  of  the  same  quan- 
tity— that  is,  if  the  tilting  has  been  uniform  throughout,  as  we  have 
assumed — then  the  probable  error  of  tlie  determined  value  of  that 
quantity  (0.42  foot)  is  less  than  ±0.05  foot. 


VI  i 


OILIIEIIT.I 


RATE    OF    MOVEMENT. 


637 


Tlio  most  important  factors  tending  to  throw  doubt  on  the  (•oiulnsion 
are  the  possibilities  of  accidental  change  in  the  various  beuclics  to 
which  the  measurements  are  referred.  The  bcncli  at  Port  Austin, 
being  a  marlc  on  bed  roclc,  is  trustworthy,  and  the  agreement  between 
the  three  benches  used  at  Escanaba  is  good  evidence  of  their  stabil- 
ity; but  the  bench  at  Milwaukee,  with  which  bntli  are  conijjared,  is  a 
pier  of  a  bridge  in  daily  use  and  may,  perhaps,  be  slowly  settling.  If 
it  is  settling,  the  comparisons  with  benches  at  Kscanaba  and  Port  Aus- 
tin may  merely  reveal  that  fact  and  not  measure  tlie  subsidence  of  the 
land.  The  fact  that  the  swing  bridgoon  the  jiitr  has  not  required  re  lev- 
eling is  certainly  favorabh*  to  the  stability  of  the  pier,  especially  when 
it  is  considered  that  a  change  of  fully  lA  inches  is  to  bo  accounted  for; 
and  there  is  further  conliriuation  in  the  discovery  of  a  discrepancy 
between  ^lilwaukee  and  Escanaba  by  Captain  ^Marshall,  whose  data 
are  probably  independent  of  the  check  mark.  Of  the  benches  on  Lake 
Erie,  the  one  at  l*ort  Colborne  is  satisfactory,  but  those  at  Cleve- 
land may  have  settled  at  critical  times,  and  if  so  their  change  would 
intiuence  the  result  in  the  direction  found.  Of  the  benches  on  I.ako 
Ontario,  the  one  at  Charlotte  is  eminently  stable;  the  oidy  practical 
question  atTccts  the  bench  at  Sacketts  Harbor,  which  is  on  a  building 
that  has  not  been  wiiolly  stable  since  its  construction,  although  pre- 
sumably s(t  since  the  making  of  the  bench.  If  the  buikPr,  at  Sacketts 
Harbor  scttleil  between  1874  and  ISitG,  the  etfect  cf  the  lowered  bench 
was  to  i)ro(luce,  not  sucli  a  change  as  appears  from  the  measurements, 
but  one  with  the  opposite  sign. 

It  seems  to  me  that  the  harmony  of  the  measurements  and  tlieir 
agreement  with  inedictioii  from  geologic  data  make  so  strong  a  case  for 
the  hypothesis  of  tilting  that  it  should  be  accepted  as  a  fact,  despite 
the  doubts  concerning  the  stability  of  the  gages. 


1      il 


KATK   itV    MOVKMKXT. 

The  deduced  mean  rate  of  change — 0.-12  foot  to  the  KM*  miles  in  a 
century — depends  on  assumptions  which  are  convenient  rather  than 
probable.  These  are:  (1)  'hat  the  whole  region  moves  together  as  a 
unit,  being  tilted  without  internal  warping,  and  (2)  that  the  direction 
of  its  present  tilting  is  identical  with  the  direction  of  the  total  change 
since  the  epoch  of  the  Nipissing  outlet  of  the  upjier  lakes.  What  wo 
know  of  the  general  character  of  earth  movement?^  gives  no  warrant 
for  such  assunqitions  of  uiiilbrnfity,  but  no  better  assumptions  as  to 
this  region  are  now  available.  I'liler  the  law  of  probabilities,  the 
close  agreement  of  four  measurements,  three  of  which  are  wholly  inde- 
pemlent,  gives  a  good  status  to  their  mean,  but  there  are  other  con- 
siderations tending  to  weaken  this  status.  The  probable  errors  of  the 
individual  measurements  are  rather  high,  ranging  from  It  to  .")»  per 
cent,  and  this  suggests  the  possibility  that  the  closeness  of  their  cor- 
respondence nniybe  accidental.     It  should  bo  remembered  also  that  at 


Ml  i 


^^*' 


638    EARTH  MOVKMENT  IN  THE  GREAT  LAKES  REGION, 

two  or  throe  stations  there  was  reason  to  beliftve  that  the  gage  zeros 
were  settling  during  tiie  period  in  wliich  tlie  observations  were  made, 
and  till-  residts  involve  the  doubtl'ul  assumption  that  the  rate  of  set- 
tling was  uniform.  There  is  room  for  doubt  as  to  the  precision  of  the 
instrumental  leveling;  in  only  a  few  instances  is  the  fact  of  dupiifute 
measure  nents  recorded,  and  single  measurements  are  notoriously 
insecure.     Va-vov  was  doubtless  admitted  by  ignoring  the  eft'ects  of 

bar etrie  gradient.     Hiver  floods  may  have  introduced  errors.     In 

the  absence  of  Hood  records  the  records  of  rainfall  at  Rochester  (near 
Charlotte),  Clevelaml,  and  Milwaukee  were  compared  with  the  gage 
readings,  the  results  showing  only  that  if  fiood  errors  are  involved 
they  must  be  small.  There  may  also  be  per.soinil  eiinations  of  observ- 
ers, especially  as  the  gages  at  pairs  of  stations  were  not  in  every  case 
of  the  same  type,  i'^or  all  tb'  se  reasons  I  am  disposed  to  ascribe  only 
a  low  onler  of  precision  to  tin  .educed  rate  of  change,  atid  regard  it 
as  indicating  the  order  of  magr.tude  rather  than  the  actual  magnitude 
of  the  diti'erential  movement. 

The  rate  of  change  indicattil  by  Stuntz's  observations  is  more 
rapid.  As  already  quoted,  he  stares  that  at  a  time  when  Lake  Supe- 
rior was  exceptionally  low  at  its  outlet,  it  was  nevertheless  so  high 
at  its  western  extreu)ity  as  to  obliterate  from  the  St.  Louis  River  a 
rapid  which  had  been  visible  oidy  a  few  years  before.  This  statement 
involves  no  definite  mejisures,  but  it  implies  that  the  change  within  the 
memory  of  individuals  involves  feet  rather  than  the  inches  deduced 
from  the  studies  in  the  other  lakes.  Similar  inferences  may  be  drawn 
from  his  statement  as  to  submerged  stumps.  The  recorded  range  of 
water  level  in  Lake  Superior  is  about  n  feet,  and  trees  would  grow 
little  if  any  below  high-watermark.  If,  then,  with  low  stage  at  the 
east  end,  stumps  are  submerged  at  the  west,  a  change  of  ."»  feet  or  more 
would  seem  to  have  occurred  during  the  period  covered  by  the  growth 
of  a  tree  and  the  survival  of  its  stump.  Tlie  differences  between  the 
inferences  drawn  from  this  evidence  and  the  result  based  on  gage 
readings  on  the  other  lakes  is  so  wide  as  to  suggest  the  possibility  of 
error  in  the  Lake  Superior  observations.  It  is  certainly  important  that 
they  be  verified.  Unfortunately  I  have  not  been  able  to  visit  the 
region,  and  the  gage  records  accessible  to  me  are  not  so  connected  with 
bench  marks  as  to  give  a  satisfactory  basis  for  computation.  The 
United  States  Lake  Survey  nmde  observations  of  lake  level  at  Superior 
City  from  185!)  to*187],  and  then  trsMisferred  the  station  to  Duluth, 
where  it  was  continued  for  two  or  three  years.  No  bench  mark  at 
Duluth  is  described,  and  the  only  recorded  bench  mark  at  Superior 
City  is  ui)on  a  wooden  structure,  Johnson  &  Alexander's  sawmill.  If 
this  bench  survives,  a  good  test  could  be  made  by  renewing  tiie  gage 
station  at  Superior  City.  At  the  other  end  of  the  lake,  at  Sault  Ste. 
Marie,  there  are  authentic  benches  dating  from  1855. 

If  we  assume  that  the  rate  of  0.42  foot  per  100  miles  per  century  is 


aiLniBT.] 


RESULTING  OEOOKAPHIC   CHANGES. 


63!) 


uiiiforin  and  secular,  and  project  it  backward  to  tlie  time  when  tlie 
drainage  of  Lake  ilnron  was  sbifted  from  North  l>ay  to  Port  Huron, 
we  obtain  for  tlie  period  since  that  cliange  about  1(\<)()()  years.  Fronj 
studies  at  Niagara,  Taylor  has  estinuited  the  same  p.  "'od  as  between 
5,000  and  10,000  years;'  and  the  comparison  indi(;ates  that  the  rate  of 
nio<lern  change  is  of  such  magnitude  as  to  accord  well  with  the  idea 
that  it  merely  continues  tlie  geologic  change. 

It  is  to  be  hoped  that  eventually  a  better  measure  of  the  rate  of 
tilting  and  a  surer  indication  of  its  direction  may  be  obtained,  but  even 
with  present  knowledge  there  is  interest  and  prolit  in  considering  the 
economic  and  geographic  consequences  of  the  tilting. 


GK<iGRAPIIIC    CIIAXOES    RESUJ^l'ING    TBOM    THE    MOVli- 

aiENT. 

Assuming  that  the  general  result  of  this  investigation  is  substan- 
tially correct — that  the  whole  lake  region  is  being  lifted  on  one  side  or 
(lei)ressed  on  the  other,  so  that  its  plane  is  bodily  canted  toward  the 
south-southwest,  and  that  the  rateof  change  is  such  that  the  two  ends 
of  a  line  100  miles  long  and  lying  in  a  south  southwest  direction  arc 
relatively  displaced  four-tenths  of  a  foot  in  100  years— certsi in  general 
conse(ineiices  nuiy  bo  stated.  The  waters  of  each  lake  are  gradually 
rising  on  the  southern  and  western  shores  or  falling  on  the  northern 
and  eastern  shores,  or  both.  This  change  is  not  directly  obvious, 
because  masked  by  temporary  changes  due  to  inequalities  of  rainfall 
and  evajioration  and  varicms  other  causes,  but  it  affects  the  mean 
height  of  the  lake  surface.  In  Lake  Ontario  the  water  is  advancing 
on  all  shores,  the  rate  at  any  jtlaco  being  proportional  to  its  distance 
from  the  isobase  through  the  outlet  (AA,  fig.  100.  ]>.  (ItO).  Atiramilton 
and  Port  l)a"iousie  it  amounts  to  0  inches  in  a  century.  The  water 
also  advances  on  all  shores  of  Lake  ICrie,  most  rapidly  at  Toledo  and 
Sandusky,  where  the  change  is  8  or  0  inches  a  century.  All  about 
Lake  Huron  the  water  is  falling,  nn)st  rapidly  at  the  north  and  nofth- 
east,  where  the  distance  from  tiie  I'ort  Huron  isobase  (CO,  fig.  100)  is 
greatest;  at  IMackinac  the  rate  is  (» inches,  and  at  the  mouth  of  I'rench 
Kiver  10  inches,  a  century.  On  Lake  Superior  tlio  isobase  of  the 
outlet  (1)1),  fig.  100)  cuts  the  shore  at  the  international  boundary;  the 
water  is  advancing  on  the  Amev  !an  shore  and  sinking  on  the  Cana- 
dian. At  Duluth  the  advance  is  0  inches,  and  at  Heron  I>ay  the  reces- 
sion is  5  inches,  a  century.  The  shores  of  Lake  Michigan  are  divided 
by  the  Port  Huron  isobase.  North  of  Oconto  and  -Manistee  the  water 
is  falling;  south  of  those  places  it  is  rising,  the  rate  at  ililwaukee 
being  5  or  (i  inches  a  century,  and  at  Chicago  !)  or  10  inches.  Event- 
ually, unless  a  dam  is  erected  to  prevent.  Lake  Jlichigan  will  again 
overflow  to  the  Illinois  Kiver,  its  discharge  occupying  the  channel 


1    ll 


I  Dull.  GboI.  Soc.  America,  Vol.  IX,  IsgS,  p.  83. 


G40  KABTir    MOVKMKNT    IN   THK    (iRKAT   LAKKS    RKOION. 

ciuvcd  l.ytlie  outlet  ofii  ridstoconc,  Klaciiil  laki'.  Tlio  smnmit  in  that 
cliaiiiiil  is  now  «  I'eet  above  the  mean  level  of  the  lake,  and  the  time 
before  it  will  bo  overtopped  (under  the  stated  assumption  as  to  rate  of 
tiltiiifr)  may  be  computed.  Evineutly  the  flr.st  water  to  overflow  will 
bo  tliat  of  some  high  stage  of  the  lake,  and  the  disehargo  may  at  (Irst 
be  intermittent.  Sueh  high-water  discharge  will  occur  in  500  or  «00 
years.  For  the  mean  lake  stage  such  discharge  will  begin  in  about 
1,000  years,  and  after  1,500  years  theie  will  be  no  iuterruptiou.  In 
about  2,000  years  the  Illinois  Eiver  and  the  Niagara  will  carry  e(iual 
jiortions  of  the  siu'i)lus  water  of  the  Great  Lakes.  In  2,500  years  the 
(lisihaige  of  f  lie  Niagara  will  bo  intermittent,  failing  at  low  stages  of 
the  lake,  and  in  .i.-^OO  years  tiiere  will  be  no  Niagara.    The  basin  of 


lj;| 


OiiUiM^ 


^tmAtLsky 


Fi(f.  100.— KelntioiiH  of  tlio  Bliori's  of  tlio  Great  LiikOB  to  the  i^obascB  drawn  through  their  outlets. 

Lake  Erie  will  then  be  tributary  to  Lake  Huron,  the  current  being 
reversed  in  the  Detroit  and  St.  Clair  channels. 

The  most  numerous  economic  bearings  of  tliis  geographic  change 
pertain  toengineering  works,  especially  for  the  i)reservation  of  harbors 
and  regulatiim  of  water  levels.  But  the  modilications  thus  produced 
are  so  slow  as  compared  to  the  growing  denumds  of  connnerce  for  depth 
of  water  that  they  may  liave  small  imi)ort<ance.  It  is  a  matter  of  greater 
moment  that  cities  and  towns  built  on  lowlands  about  Lakes  Ontario, 
Erie,  Jlichigan,  and  Superior  will  sooner  or  later  feel  the  encroachment 
of  the  advancing  water,  and  it  is  peculiarly  unfortunate  that  Chicago, 
the  largest  city  on  the  lakes,  stands  on  a  sinking  plain  that  is  now  but 
little  above  the  high-water  level  of  Lake  Michigau. 


m\  i 


oiLimnrl    NKKU    OK    AND    I'LAN8    FOK    PHKCISK    MKASIIHKMENT. 


641 


ITiAXS    lou   PUKCIsr,  MKASIltKMKXI'. 

Wliilo  it  in  believed  tliat  tiie  {jt'iicral  I'lift  ot'  ('iiitii  iiiuvciiu'iit  lias 
been  estalilislii'd  liy  tlie  present  investigation,  tlio  iiieasurcnient  of  lis 
rate  and  tliedcteiinination  of  its  direction  full  far  slant  ot"  tiie  iirnision 
wliicli  is  dcsiralde.  lun-  the  i)uri)(>sesot'scien<'('  tlieordcrofniagnilndo 
of  tlni  ciianye  is  more  iniiioitant  than  its  precise  nn'asnrenuMit.  hut 
there  are  involved  nr^at  economic  interests,  and  tlie.-e  demand  irioro 
delinite  inl'ornnition.  The  account  of  the  present  in  vestitcation  is  there- 
lore  snpphMnciited  hy  an  ontiine  ])lan  of  the  more  elaborate  iiivestij^a- 
tion  which  appears  necessary  to  give  nu'asiu'ements  of  tiie  inecis'on 
that  is  desirable. 

Mxistin;;'  tlata  are  ntithei'  fall  enongli  nor  exact  enon{,'h  to  ^ive  satis- 
factory measures  ot'  tiie  small  ([nantities  son};ht.  Doubtless  a  more 
elabcnate  disenssion  would  yield  better  results  than  I  have  obtained, 
but  the  improvenu'nt  could  not  be  y;reat.  Observations  by  the  I.ako 
Survey  were  eoinhu'ted  for  purposes  notdemandin^ahiK'h  order  of  pre- 
cision, and  hij,'h  relincment  was  not  attempted.  The  supplementary 
v.ork  done  in  IH'.HI  attemi)ted  only  to  bo  good  eiioujili  for  use  in  comlii- 
natiini  with  the  work  of  1S74  and  ISTti,  and  can  not  serve  as  the  lirst 
term  of  a  lU'W  comparison.  The  problem  rerjuires  a  new  set  of  hi;;h- 
fiiad'.  observations  at  each  station  of  a  carefully  jilaiined  system,  to  bo 
f(  Mowed,  after  an  interval  of  at  least  adecade,  by  asecond  set  of  observa- 
tions at  the  same  stations. 

Foreseeing  no  oi»i)()rtunity  to  undertake  such  a  work  niysclt.  J  havo 
formulated  in  the  following  jiaragraphs  a  [)lan  embodying  the  results 
of  my  experience — iiplan  iuteinled  to  allbrd  useful  suggestions  to  some 
investigator  by  whom  the  work  nmy  bo  actn.ally  undertaken. 

Silccfidii  of  HfatioHx. — To  measure  the  rate  of  change  in  any  given 
direction,  observations  at  two  stations  siitlice;  but  todetermino  also  the 
direction  of  change,  it  is  necessary  to  use  three  stations  grouped  in  the 
form  of  a  triangle.  The  longer  the  sides  of  the  triangle  the  better 
the  ineasurenn'ut  of  rate,  ami  the  larger  its  smallest  angle  the  better 
the  determination  of  direi;tion.  A  brief  inspet'tion  shows  that  tho 
shores  of  Lake  Michigan  and  Lake  Huron  give  the  best  opportunity 
for  the  planning  of  ii  well-conditioned  triangle.  Though  the  narrow- 
ness of  their  connecting  strait  has  led  to  the  giving  of  separate  names, 
they  are  really  a  single  lake,  and  the  stretch  of  their  water  surface  is 
in  every  direction  greater  than  that  of  Lake  Superior. 

For  the  ])urpose  in  view  the  point  of  first  importance  is  the  outlet  of 
the  lake  at  I'ort  lluron.  This  is  peculiar  in  that  the  plane  of  mean 
water  level  has  here  a  C(mstant  relation  to  the  adjacent  land,  a  relation 
altogether  independent  of  the  progressive  deformation  of  the  basin. 
This  station  should  not  be  on  the  St.  Clair  Eiver,  but  on  the  shore  of 
the  lake  near  by. 

18  GEOL,  I'T  L' 41 


Mlii: 


f 


i! 


G42  EAUTH   MOVE^rKNT   IX   THE   fiREAT   1,AKES   REGION. 

Tlie  second  point  of  vantage  is  <  'hicaso.  As  economic  interests  are 
more  sciionslv  allectod  l).v  tlio  ocfrniphic  cliaiifre  at  that  point  than 
elsewlii-if,  it  "is  desirable  to  determine  diroetly,  l)y  comparison  with 
Port  Huron,  the  rate  at  wliidi  ilie  lake  is  encroacliinjj-  on  the  land. 

A  tliird  point  of  prime  importance  is  the  Strait  of  Mackinac. 
Altiiongb  the  e(piilibrinm  levels  of  the  surfaces  of  the  two  lakes  are 
the  sanre.  there  are  considerable  periods  when  their  equilibrium  ia  dis- 
turbed, and  during  such  jieriods  a  current  Hows  in  one  dirc<'tion  or  the 
other  through  the  strait.  Only  when  this  current  is  nil  is  the  whole 
water  body  in  perfect  oiiuilibrinm,  and  it  is  essential  to  p  cise  levelinjf 
through  t  iie  water  surfa.e  eitiicr  that  times  of  e(iuilibriniu  be  chosen  or 


Vlii.  101.— I'mpuned  s_\  rtleins  of  staliniis  lor  (lio  jiriTiso  nii'ai^lirtMiii'iit  <<('  i-jirlii  riM»\iini-ntH. 

that  due  allowance  be  made  for  the  ;fradients  associated  with  tlow. 
Observations  must  therefore  be  nnide  on  the  current  in  the  strait,  and 
it  is  best  to  connect  them  witli  the  work  of  a  complete  station. 

As  a|i])earsby  the  annexed  diaj-ram  (fi};.  101).  the  trian};le  formed  by 
these  tliree  stations  is  well  conditioned  as  to  size  and  form ;  the  len<;ths 
of  its  sides  are  appioximately  225,  275,  and  JHO  miles,  and  its  smallest 
anf;le  is  about  lii  degrees. 

While  the  j)roper  use  of  these  three  stations  will  give  answer  to  tlio 
questions  of  greatest  ec(niomic  and  scientilii;  importance,  there  will  be 
nmterial  scientillc  advantage  in  adding  a  fourth  station  to  the  system. 
It  should  be))laced  somewhere  on  the  north  shore  of  (ieorgian  Hay,  and, 


01I.nF.IlT.  1 


PLANS    FOK    PRECISE    MKASURK>I?:NT. 


643 


^, 


J 


•*'  . 


giving  consideration  to  accessiliility  as  well  as  };i'<'};'''>iplii"'  ])osition,  it 
is  |)robable.  that  I'arry  Sound  slioiild  be  selected,  liy  addinj;'  this  sta- 
tion another  well-conditioned  triangle  woidd  be  (uimpleted,  and  there 
would  result  an  additional  determination  of  tlie  rate  and  direction  of 
tilting.  If  rate  and  diiection  vary  from  iilace  lo  jilace  the  fact  will 
]irobal)ly  be  l)rought  out.  There  would  be  additional  advantage  in  the 
fact  tiiat  I'arry  Sound  and  Chicago  are  separated  by  the  greatest  \n'iw- 
ticalde  distance  in  the  direction  of  ma.xinnim  change,  so  that  a  coiii- 
]taratively  short  ])erioil  of  time  might  afl'ord  a  valuable  measiireiiient. 
The  approximale  results  of  tlie  present  investigation  indicate  tliat  the 
change  in  tlie  relative  leiglit  of  Parry  Sound  and  Chicago  in  ten  years 
would  be  about  2  inchc! . 

Conilitioiis  ciiiitrolliiiii  ciinipmiiit. —  In  order  to  jilan  intelligently  the 
system  of  observations,  full  consideration  should  be  given  to  the  con- 
ditions arte<'ting  the  iiroblem.  and  pro\'ision  should  lie  made  for  all 
jtossible  sources  of  error.  Prominent  among  tliese  are  the  various  fac- 
tors which  modil'y  the  water  level  at  points  on  the  lake  shore.  Sin'h 
factm's  have  been  considered  in  the  jireceding  discussion  of  gage  data, 
but  they  are  assembled  lieii^  in  a  more  systematic  way. 

Tlie  lake  continually  receives  water  from  streams  and  from  rain,  and 
continually  parts  with  water  by  discharge  at  its  outlet  and  by  eva!>ora 
tion.  In  the  long  run  gain  and  loss  are  eipial,  but  for  short  periods 
tliey  are  usually  iineciual:  so  that  Irom  ibiy  to  day.  from  season  to 
season,  and  from  year  to  year  the  volume  of  the  lake  and  the  cnnse- 
(pient  mean  level  of  its  snrtace  are  <'ontinuall\'  changing. 

lu  bays  and  estuaries  there  are  local  temporary  \  ariations  occasioned 
by  the  Hoods  of  tributary  sti'eams. 

There  are  solar  and  lunar  tides,  snnill  as  compared  to  those  of  the 
ocean,  but  not  so  small  that  they  may  be  neglected. 

The  wind  pushes  the  lake  water  before  it,  jiiling  it  u])  on  lee  shores 
and  lowering  the  level  on  weather  sliores.  During  great  storms  these 
changes  have  a  magnitude  of  several  feet,  and  the  effect  of  light  wind 
la  distinctly  appreciable.  I'^ven  the  land  and  sea  lireezes,  set  up  near 
the  shore  by  contrasts  of  surface  temperature,  have  been  found  to  pro- 
duce measurable  ell'ects  on  the  water  level. 

There  is  also  an  iiilluence  from  atmosiilieric  pressure.  W'lien  the  air 
is  in  eipiilibrium,  if  that  ever  occurs,  the  iiressnre  is  the  same  on  all 
parts  of  the  lake  surface,  and  the  eiiuilibrium  of  the  lake  is  not  <lis- 
turbed  :  but  when  the  air  pressure  varies  I'roni  iioint  to  point  tliis\aria- 
tioii  of  pressure  is  a  factor  in  the  eipiilibrium  of  the  water  surface,  the 
surface  being  coiii]iaratively  dejiressed  where  the  air  pressure  is  greater 
and  elevated  where  it  is  less. 

Wlu-n  a  storm  wind  (teases,  the  water  not  merely  tlows  back  to  its 
normal  |tosition  but  is  carried  by  nioinentum  beyond,  and  an  oscilla- 
tion is  thus  set  up  which  continues  for  an  iiidetinile  period.  A  similar 
oscillation  is  started  whenever  the  e<|nilibrinni  is  disturbed  by  diller- 


m 
■m 


% 


m\  (' 


.*i*^f 


644  EARTIf    MOVEMKNT    IN   THE    GHEAT   LAKES    REGION. 

eu(!es  of  atmosplieiic  i)res.sme:  and  these  swaying  motions,  called 
scielies,  analogous  to  the  swayiiiK'  of  water  in  a  tub  or  hand  basin, 
Itersist  for  long  iieriods,  In  fact,  tliey  bridge  over  the  intervals 
from  impulse  to  impulse,  so  that  the  water  of  tlie  (Ireat  Lakes  never 
comes  to  rest. 

Every  disturbance  wliieh  causes  the  water  to  rise  on  one  shore  of  the 
lake  and  full  on  the  otiier  interferes  with  the  eiinilibriuni  between  the 
two  lakes  at  tiie  Mackinnc  Strait.  If  a  strong  wind  blows  the  water 
easlwiird.  raising  the  level  on  tiie  east  shores  of  the  hikes  and  lowering 
it  on  the  west  shores,  tliere  is  high  water  at  the  west  end  of  the  strait 
and  low  water  at  the  east,  in-odneing  a  current  toward  the  east;  and 
when  tlie  wind  cciiscs  tiie  water  that  has  poured  from  Lake  Michigan 
to  Lala-  Huron  nmsr  leturn.  jiroducing  a  current  in  the  opposite  direc- 
tion. 'I'heoretically,  analogous  ellects  sliould  be  ])roduced  by  tides  and 
biirometric  gradients,  and  there  can  be  little  <piestion  of  their  detection 
if  the  phenonicna  at  tlie  strait  are  studied. 

These  various  intluences  worii  inde])endently  but  siinultaneously.  and 
their  etVc'ts  iire  blended  in  the  uclual  oscillations  of  the  water  surface 
at  any  jroint.  In  nsing  the  wuter  surface  for  the  imrpose  of  precise 
leveling,  it  is  necessary  to  titlie  account  of  all  such  fuctors  and  make 
provision  for  the  avoidance  or  coriection  of  the  errors  they  tend  to 
produce. 

V<\m\)mvni, — In  view  of  the  complexity  of  the  phenomena  to  be  ana- 
lyzed, it  is  desirable  that  most  of  tiie  instruments  employed  be  of  the 
automatic  kind,  giving  continuous  record.  While  such  instriiinents 
accomplish  much  more  than  could  be  done  by  an  observer  alone,  they 
do  not  dispense  with  his  services.  They  are  complex  as  compared 
to  the  a)t])a:iitiis  for  iiersonal  observation,  and  can  be  successfully 
employed  only  by  a  inaii  of  scieiitilic  training.  The  iirst  essential, 
tliei'efore,  at  each  of  the  stations  is  an  expert  observer. 

The  gage  employed  for  tin;  determination  of  water  height  should  be 
of  some  automatic  type.  g'i\  ing  a  conliiiiious  record.  This  is  necx'ssary 
in  order  that  the  study  of  the  record  may  fuinisli  data  for  the  comph'te 
elimination  of  errors  I'roni  tides,  seiches,  and  land  and  sea  breezes.  The 
gage  should  be  protected,  not  only  from  the  direct  shock  of  waves,  but 
from  all  secondary  agitation  of  the  water  due  to  wave  shock.  It  should 
be  so  installed  as  to  be  secure  from  settling.  The  height  of  its  zero 
shoulil  be  reiidily  \eri  liable. 

Xeiir  each  station  there  should  be  at  least  three  benches,  constructed 
witii  special  reference  to  jiermanence  and  stability.  They  should  be 
independent  of  one  another  and  independent  of  other  structures. 

Pressure  of  the  air  should  1)(>  continuously  recor<led  by  a  barogi'apli, 
carefully  standardized.  A  wind  vane  iiiid  aneinouieter  should  give 
automatic  records. 

At  MaekiiuK!  there  should  also  be  means  lor  securing  a  record  of  the 
direction  and  velocity  of  water  currents. 


\ 


K. 


■  I    ( 


•g 


% 


'"-v. 


nlLBERT] 


moseley's  investigation. 


645 


Treatment  of  ohna-ra t ions.— ^tri^ss  liaving  already  been  laid  on  the 
importance  of  putting  the  work  in  expert  hands,  it  would  be  unwise  to 
attempt  the  formulation  of  a  eodeot  instructions  for  either  the  making 
or  the  reduction  of  observations;  but  there  may  be  advantage  in  a  few 
suggestions  based  on  experience  acquired  in  the  present  investigation. 

While  it  is  doubtless  possible  to  d'-duce  from  a  study  of  ('urrents  in 
Mackinac  Strait  a  theory  of  the  relation  of  those  currents  To  the  equi- 
librium coiulitions  of  the  two  lakes,  it  will  probably  be  found  best  to 
use  the  current  observations  chiefly  for  the  discrimination  of  favorable 
and  unfavorable  times,  and  to  compare  the  lake-level  observations  only 
for  times  when  the  current  at  Mackinac  is  gentle.  It  will  also  be  better 
to  avoid  the  use  of  observations  during  the  prevalence  of  strong  winds 
or  high  barometri(!  gradients  than  to  attempt  the  ai)i»lication  of  correc- 
tions for  those  factors. 

The  times  not  barred  by  high  winds,  high  gradients,  and  currents 
will  ordinarily  not  be  found  to  have  such  duration  and  distribution  that 
tidal  effects  can  be  eliminated  by  including  complete  tidal  cycles.  It 
will  therefore  be  necessary  to  discuss  the  solar  and  lunar  tides  for  each 
station  and  prepare  tables  of  correction  to  be  api)lied  to  all  observa- 
tions employed.  The  same  treatment  will  be  necessary  for  the  elfects 
of  land  and  sea  breezes.  Barometric  gradient  of  amount  too  great  to 
be  ignored  nearly  always  exists,  and  this,  as  determined  by  observa- 
tions at  the  stations  themselves,  should  be  the  subject  of  computation 
and  correcitioM. 

Seiches  should  be  fully  discussed  for  each  station,  and  the  observa- 
tions finally  used  should  be  grouped  in  periods  of  sullicient  length  to 
eliminate  the  seiche  etlect. 

Sl'Pl'LKMKXT.-IXVESTKJATION    ]JV   Ml!.  :M<)SKM-:V. 

The  main  body  of  manuscript  for  this  paper  was  preitared  in  .lune 
and  July,  1897.  An  abstract  was  communicated  in  August  to  the 
American  Association  for  the  Advancement  of  Science,  meeting  in 
Detroit,  and  a  fuller  abstract  was  printed  in  the  September  number  of 
the  National  Geographic  Magazine.'  As  a  result  of  this  publication 
I  became  ac<iuainted  with  a  cognate  investigation  by  10.  L.  ^loseley, 
of  Sandusky,  Ohio.  His  data  and  results  were  communicated  to  the 
Ohio  Academy  of  Sciences  in  December,  1897,  and  printed  so(ni  after- 
wards in  a  Sandusky  newspaper.  They  received  more  permanent  as 
well  as  fuller  i)resentation  in  an  article  contributed  to  the  liakeside 
Jlaga/.ine,^  au<l  this  article  reaches  me  while  the  proof  sheets  of  the 
l>resent  paper  are  in  hand.  As  will  be  readily  understood  from  the 
lidlowing  abstract,  the  data  he  has  gathered  constitute  an  important 
contribution  to  the  subject. 


'MiHlltli'utiiin  cil'  I  hi'  ilroiil  Lakes  liyiMirtli  mciviniini  i  Nal.  lioog.  Mog.,  SBptonilii'r,  IHiiT.  \'ul.  VTtl, 
lip.  2:::t-'J47. 

■'  Liikt'  Krin  iMiIrtruinjj:  the  i-*Irtiuls  si'imnited  rniiii  tho  nminluiiit  In  rcreiit  tiini'^;  \>y  Iv  I*.  Mtiscleyj 
Tku  Lukonide  Mui;u/.iiii',  Liikosiilo,  <>liii>.  April,  IK9K,  Vul.  I,  |i|),  14-lT. 


■  I      ( 


I  i 


I'f 


646 


EARTH    MOVKMENT    IX    THE    (;',;    -T   LAKES   RE(iION. 


North  of  Sandusky  Buy.  near  the  west  end  of  Lake  Erie,  is  a  cluster 
of  islands,  of  which  the  live  largest  are  each  several  miles  in  extent.' 
About  them  tlie  water  is  shallow,  and  if  the  lake  were  lowered  30  to  35 
feet  they  would  all  be  connected  with  the  mainland.  On  these  islands 
grow  many  species  of  wild  plants,  and  the  origin  of  this  Hora  is  related 
to  the  geologic  history  of  the  islands.  There  was  a  time  during  the 
ice  retreat  v.lien  the  whole  l)asin  was  covered  by  a  glacial  lake.  If  the 
water  was  gradually  lowered  fiom  the  plane  of  the  glacial  lake  to 
the  present  plane  of  Lake  I'hie,  the  islands  were  at  first  barren  and 
were  eventually  occui)ied  only  by  such  jdants  as  were  in  .some  way 
conveyed  across  the  intervening  straits,  from  I'.i  to  3  miles  wide.  As 
^loseley  points  out,  theic  arc  many  modes  of  such  adventitious  intro- 
duction, but  they  could  not  be  expected  to  give  to  tlie  islands  a  liora  so 
varied  as  that  of  the  adjacent  mainland. 

If,  on  the  oilier  hand,  as  inferred  IVom  the  slopes  of  the  old  shore  lines 
and  other  data,  the  altitude  of  the  land  was  dillerent  when  the  glacial 
lake  was  drained  away,  the  origimil  Lake  ICrie  occinpied  only  the 
eastern  part  of  the  I'hie  basin,  and  tiie  western  part,  including  the  dis- 
tiictof  the  ishmds,  was  dry  land.  Subsequently,  from  the  tilting  of 
the  land,  the  lake  walers  advanced  westward  so  as  to  Hood  the  straits 
and  convert  the  lowland  hills  into  the  present  islands.  !n  connection 
with  such  a  geologic  history  the  islands  would  have  accpiired  their 
flora  a''  the  same  time  with  the  mainland,  and  siionld  now  present  the 
same  variety  of  s])ecies,  so  far  as  local  conditions  iiermit.  iMoseley  has 
careful ly  compand  the  insular  Hora  with  that  of  the  nniinland,  and 
finds  that  Ihe  only  nniinland  si)ecies  which  do  not  occur  on  the  islands 
are  such  as  do  not  tind  there  a  congenial  soil,  Tiie  botanic,  evidence 
thus  supports  the  geologic,  and  verilies  the  conclusion  that  the  land 
has  been  tilted  toward  the  southwest  since  the  birth  of  Lake  Erie. 

The  islands  are  conii)osed  largely  of  limestone  and  are  surrounded 
by  limestone  cliffs.  In  f-'outh  Bass  or  Put-in  Bay  Island  there  are  caves 
opening  at  the  water's  edge  and  \  tly  (tccupied  by  lake  water. 
Exploring  these,  Moseley  finds  stalactites  exteinling  from  the  roof  down 
into  the  water,  and  stalagmites  lying  3  or  i  feet  below  the  present  sur- 
face of  the  lake.  Compiring  the  present  water  level  with  the  lowest 
levels  known  in  recent  times,  it  appears  that  these  stalagmites  have 
not  been  above  water  during  the  present  century,  and  as  stalagmites 
are  formed  only  in  the  air.  it  is  clear  that  the  lake  has  encroached  on  the 
land  since  they  were  nuide. 

These  data  show  only  that  a  change  has  occurred,  and  ascribe  no 
date,  but  other  phenomena  observed  in  tin-  neighborhood  of  Sandusky 
indicate  clearly  that  change  is  now  in  progress.  A  tract  of  land  on 
which  hay  was  nuule  in  1828  is  now  permanently  under  water.  A  tract 
of  land  onclmlf  mile  scpuire,  surveyed  in  18(){>,  has  since  become  marsh, 
with  water  and  niiid  12  to  18  inches  deep.    Various  parts  of  Sandusky 

'  Korlhc'  reliitiiin  ot'thuaii  jhUiiiIh  to  tliv  laku  anil  the  iMubiimi  iiI'Iih  <miIU'I,  mv  llg.  MO,  \i.  640. 


f'    I 


if  I 


OII.IIEKT.  I 


MOSKLEy'S   INVESTIGATION. 


647 


Hay  wbere  nt"ii<is  grew  withiu  the  memory  of  iiioii  still  living-  are  now 
covered  with  open  water.  "  By  the  high  water  that  prevailed  in  1858 
to  1800  large  trees  were  killed  in  many  places  where  the  waves  could 
not  reach  them."  "  nmulreds  of  walnut  stumps  are  still  standing  on 
the  border  of  the  marshes  east  of  Sandusky  where  even  now,  alfliimgh 
the  water  is  lower  than  usual,  it  is  too  wet  for  walnut  trees  to  grow. 
One  that  stood  recently  on  ground  only  G  inches  above  the  present  lake 
level  measured  5  feet  i  inches  in  diameter.  We  may  infer  from  tliis 
tiiat  during  the  life  of  this  tree,  probably  over  300  years,  the  water  was 
not  so  high  as  in  the  [)resent  century.'"  JIany  stum|)s  and  prostrate 
trunks  with  roots  and  branches  attached  are  found  from  1  to  •!  feet 
below  the  present  lake  level,  and  in  one  locality  it  is  inferred  that  the 
lake  during  the  life  of  the  trees  must  have  I  en  as  nnu'h  as  8  feet  lower 
than  '    firing  much  of  the  time  for  the  last  forty  years." 

Tliese  vario\is  facts,  and  others  of  the  same  tenor  enumerated  by 
Moseley,  are  in  complete  accord  with  the  (lualitative  results  derived 
from  the  discussion  of  gage  readings,  but.  like  the  data  gathered  by 
8tuntz,  they  suggest  a  more  rapid  rate  of  change  tliau  do  thttse  results. 


il  ' 


